68.13.9 - dom

dom/animation/Animation.cpp

@@ -17,6 +17,7 @@
 #include "mozilla/AutoRestore.h"
 #include "mozilla/DeclarationBlock.h"
 #include "mozilla/Maybe.h"       // For Maybe
+#include "mozilla/StaticPrefs_dom.h"
 #include "mozilla/TypeTraits.h"  // For std::forward<>
 #include "nsAnimationManager.h"  // For CSSAnimation
 #include "nsComputedDOMStyle.h"
@@ -60,13 +61,13 @@ class MOZ_RAII AutoMutationBatchForAnimation {
   explicit AutoMutationBatchForAnimation(
       const Animation& aAnimation MOZ_GUARD_OBJECT_NOTIFIER_PARAM) {
     MOZ_GUARD_OBJECT_NOTIFIER_INIT;
-    Maybe<NonOwningAnimationTarget> target = aAnimation.GetTargetForAnimation();
+    NonOwningAnimationTarget target = aAnimation.GetTargetForAnimation();
     if (!target) {
       return;
     }
 
     // For mutation observers, we use the OwnerDoc.
-    mAutoBatch.emplace(target->mElement->OwnerDoc());
+    mAutoBatch.emplace(target.mElement->OwnerDoc());
   }
 
  private:
@@ -81,12 +82,13 @@ class MOZ_RAII AutoMutationBatchForAnimation {
 //
 // ---------------------------------------------------------------------------
 
-Maybe<NonOwningAnimationTarget> Animation::GetTargetForAnimation() const {
+NonOwningAnimationTarget Animation::GetTargetForAnimation() const {
   AnimationEffect* effect = GetEffect();
+  NonOwningAnimationTarget target;
   if (!effect || !effect->AsKeyframeEffect()) {
-    return Nothing();
+    return target;
   }
-  return effect->AsKeyframeEffect()->GetTarget();
+  return effect->AsKeyframeEffect()->GetAnimationTarget();
 }
 
 /* static */
@@ -363,9 +365,15 @@ void Animation::UpdatePlaybackRate(double aPlaybackRate) {
 
   mPendingPlaybackRate = Some(aPlaybackRate);
 
-  // If we already have a pending task, there is nothing more to do since the
-  // playback rate will be applied then.
   if (Pending()) {
+    // If we already have a pending task, there is nothing more to do since the
+    // playback rate will be applied then.
+    //
+    // However, as with the idle/paused case below, we still need to update the
+    // relevance (and effect set to make sure it only contains relevant
+    // animations) since the relevance is based on the Animation play state
+    // which incorporates the _pending_ playback rate.
+    UpdateEffect(PostRestyleMode::Never);
     return;
   }
 
@@ -387,8 +395,9 @@ void Animation::UpdatePlaybackRate(double aPlaybackRate) {
     //   moving. Once we get a start time etc. we'll update the playback rate
     //   then.
     //
-    // All we need to do is update observers so that, e.g. DevTools, report the
-    // right information.
+    // However we still need to update the relevance and effect set as well as
+    // notifying observers.
+    UpdateEffect(PostRestyleMode::Never);
     if (IsRelevant()) {
       MutationObservers::NotifyAnimationChanged(this);
     }
@@ -639,18 +648,18 @@ void Animation::CommitStyles(ErrorResult& aRv) {
     return;
   }
 
-  Maybe<NonOwningAnimationTarget> target = keyframeEffect->GetTarget();
+  NonOwningAnimationTarget target = keyframeEffect->GetAnimationTarget();
   if (!target) {
     return;
   }
 
-  if (target->mPseudoType != PseudoStyleType::NotPseudo) {
+  if (target.mPseudoType != PseudoStyleType::NotPseudo) {
     aRv.Throw(NS_ERROR_DOM_NO_MODIFICATION_ALLOWED_ERR);
     return;
   }
 
   // Check it is an element with a style attribute
-  nsCOMPtr<nsStyledElement> styledElement = do_QueryInterface(target->mElement);
+  nsCOMPtr<nsStyledElement> styledElement = do_QueryInterface(target.mElement);
   if (!styledElement) {
     aRv.Throw(NS_ERROR_DOM_NO_MODIFICATION_ALLOWED_ERR);
     return;
@@ -658,16 +667,16 @@ void Animation::CommitStyles(ErrorResult& aRv) {
 
   // Flush style before checking if the target element is rendered since the
   // result could depend on pending style changes.
-  if (Document* doc = target->mElement->GetComposedDoc()) {
+  if (Document* doc = target.mElement->GetComposedDoc()) {
     doc->FlushPendingNotifications(FlushType::Style);
   }
-  if (!target->mElement->IsRendered()) {
+  if (!target.mElement->IsRendered()) {
     aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
     return;
   }
 
   nsPresContext* presContext =
-      nsContentUtils::GetContextForContent(target->mElement);
+      nsContentUtils::GetContextForContent(target.mElement);
   if (!presContext) {
     aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
     return;
@@ -686,11 +695,11 @@ void Animation::CommitStyles(ErrorResult& aRv) {
   // Start the update now so that the old rule doesn't get used
   // between when we mutate the declaration and when we set the new
   // rule.
-  mozAutoDocUpdate autoUpdate(target->mElement->OwnerDoc(), true);
+  mozAutoDocUpdate autoUpdate(target.mElement->OwnerDoc(), true);
 
   // Get the inline style to append to
   RefPtr<DeclarationBlock> declarationBlock;
-  if (auto* existing = target->mElement->GetInlineStyleDeclaration()) {
+  if (auto* existing = target.mElement->GetInlineStyleDeclaration()) {
     declarationBlock = existing->EnsureMutable();
   } else {
     declarationBlock = new DeclarationBlock();
@@ -700,7 +709,7 @@ void Animation::CommitStyles(ErrorResult& aRv) {
   // Prepare the callback
   MutationClosureData closureData;
   closureData.mClosure = nsDOMCSSAttributeDeclaration::MutationClosureFunction;
-  closureData.mElement = target->mElement;
+  closureData.mElement = target.mElement;
   DeclarationBlockMutationClosure beforeChangeClosure = {
       nsDOMCSSAttributeDeclaration::MutationClosureFunction,
       &closureData,
@@ -724,7 +733,7 @@ void Animation::CommitStyles(ErrorResult& aRv) {
   }
 
   // Update inline style declaration
-  target->mElement->SetInlineStyleDeclaration(*declarationBlock, closureData);
+  target.mElement->SetInlineStyleDeclaration(*declarationBlock, closureData);
 }
 
 // ---------------------------------------------------------------------------
@@ -749,7 +758,9 @@ void Animation::SetCurrentTimeAsDouble(const Nullable<double>& aCurrentTime,
                                        ErrorResult& aRv) {
   if (aCurrentTime.IsNull()) {
     if (!GetCurrentTimeAsDuration().IsNull()) {
-      aRv.Throw(NS_ERROR_DOM_TYPE_ERR);
+      aRv.ThrowTypeError(
+          "Current time is resolved but trying to set it to an unresolved "
+          "time");
     }
     return;
   }
@@ -963,7 +974,9 @@ bool Animation::ShouldBeSynchronizedWithMainThread(
   // We check this before calling ShouldBlockAsyncTransformAnimations, partly
   // because it's cheaper, but also because it's often the most useful thing
   // to know when you're debugging performance.
-  if (mSyncWithGeometricAnimations &&
+  if (StaticPrefs::
+          dom_animations_mainthread_synchronization_with_geometric_animations() &&
+      mSyncWithGeometricAnimations &&
       keyframeEffect->HasAnimationOfPropertySet(
           nsCSSPropertyIDSet::TransformLikeProperties())) {
     aPerformanceWarning =
@@ -1048,7 +1061,7 @@ bool Animation::IsReplaceable() const {
   // We should only replace animations with a target element (since otherwise
   // what other effects would we consider when determining if they are covered
   // or not?).
-  if (!GetEffect()->AsKeyframeEffect()->GetTarget()) {
+  if (!GetEffect()->AsKeyframeEffect()->GetAnimationTarget()) {
     return false;
   }
 
@@ -1067,15 +1080,16 @@ void Animation::ScheduleReplacementCheck() {
   // If IsReplaceable() is true, the following should also hold
   MOZ_ASSERT(GetEffect());
   MOZ_ASSERT(GetEffect()->AsKeyframeEffect());
-  MOZ_ASSERT(GetEffect()->AsKeyframeEffect()->GetTarget());
 
-  Maybe<NonOwningAnimationTarget> target =
-      GetEffect()->AsKeyframeEffect()->GetTarget();
+  NonOwningAnimationTarget target =
+      GetEffect()->AsKeyframeEffect()->GetAnimationTarget();
+
+  MOZ_ASSERT(target);
 
   nsPresContext* presContext =
-      nsContentUtils::GetContextForContent(target->mElement);
+      nsContentUtils::GetContextForContent(target.mElement);
   if (presContext) {
-    presContext->EffectCompositor()->NoteElementForReducing(*target);
+    presContext->EffectCompositor()->NoteElementForReducing(target);
   }
 }
 

dom/animation/Animation.h

@@ -46,7 +46,7 @@ class Document;
 class Animation : public DOMEventTargetHelper,
                   public LinkedListElement<Animation> {
  protected:
-  virtual ~Animation() {}
+  virtual ~Animation() = default;
 
  public:
   explicit Animation(nsIGlobalObject* aGlobal)
@@ -61,7 +61,7 @@ class Animation : public DOMEventTargetHelper,
    * Utility function to get the target (pseudo-)element associated with an
    * animation.
    */
-  Maybe<NonOwningAnimationTarget> GetTargetForAnimation() const;
+  NonOwningAnimationTarget GetTargetForAnimation() const;
 
   virtual JSObject* WrapObject(JSContext* aCx,
                                JS::Handle<JSObject*> aGivenProto) override;
@@ -88,7 +88,7 @@ class Animation : public DOMEventTargetHelper,
   void SetId(const nsAString& aId);
 
   AnimationEffect* GetEffect() const { return mEffect; }
-  void SetEffect(AnimationEffect* aEffect);
+  virtual void SetEffect(AnimationEffect* aEffect);
   void SetEffectNoUpdate(AnimationEffect* aEffect);
 
   AnimationTimeline* GetTimeline() const { return mTimeline; }
@@ -98,7 +98,7 @@ class Animation : public DOMEventTargetHelper,
   Nullable<TimeDuration> GetStartTime() const { return mStartTime; }
   Nullable<double> GetStartTimeAsDouble() const;
   void SetStartTime(const Nullable<TimeDuration>& aNewStartTime);
-  void SetStartTimeAsDouble(const Nullable<double>& aStartTime);
+  virtual void SetStartTimeAsDouble(const Nullable<double>& aStartTime);
 
   // This is deliberately _not_ called GetCurrentTime since that would clash
   // with a macro defined in winbase.h
@@ -131,21 +131,16 @@ class Animation : public DOMEventTargetHelper,
 
   void Finish(ErrorResult& aRv);
 
-  virtual void Play(ErrorResult& aRv, LimitBehavior aLimitBehavior);
+  void Play(ErrorResult& aRv, LimitBehavior aLimitBehavior);
   virtual void PlayFromJS(ErrorResult& aRv) {
     Play(aRv, LimitBehavior::AutoRewind);
   }
 
-  virtual void Pause(ErrorResult& aRv);
-  /**
-   * PauseFromJS is currently only here for symmetry with PlayFromJS but
-   * in future we will likely have to flush style in
-   * CSSAnimation::PauseFromJS so we leave it for now.
-   */
-  void PauseFromJS(ErrorResult& aRv) { Pause(aRv); }
+  void Pause(ErrorResult& aRv);
+  virtual void PauseFromJS(ErrorResult& aRv) { Pause(aRv); }
 
   void UpdatePlaybackRate(double aPlaybackRate);
-  void Reverse(ErrorResult& aRv);
+  virtual void Reverse(ErrorResult& aRv);
 
   void Persist();
   void CommitStyles(ErrorResult& aRv);

dom/animation/AnimationEffect.cpp

@@ -10,6 +10,7 @@
 #include "mozilla/dom/MutationObservers.h"
 #include "mozilla/AnimationUtils.h"
 #include "mozilla/FloatingPoint.h"
+#include "nsDOMMutationObserver.h"
 
 namespace mozilla {
 namespace dom {
@@ -71,8 +72,8 @@ void AnimationEffect::SetSpecifiedTiming(TimingParams&& aTiming) {
 
   if (mAnimation) {
     Maybe<nsAutoAnimationMutationBatch> mb;
-    if (AsKeyframeEffect() && AsKeyframeEffect()->GetTarget()) {
-      mb.emplace(AsKeyframeEffect()->GetTarget()->mElement->OwnerDoc());
+    if (AsKeyframeEffect() && AsKeyframeEffect()->GetAnimationTarget()) {
+      mb.emplace(AsKeyframeEffect()->GetAnimationTarget().mElement->OwnerDoc());
     }
 
     mAnimation->NotifyEffectTimingUpdated();

dom/animation/AnimationEffect.h

@@ -16,9 +16,6 @@
 #include "nsWrapperCache.h"
 
 namespace mozilla {
-
-struct ElementPropertyTransition;
-
 namespace dom {
 
 class Animation;
@@ -35,11 +32,6 @@ class AnimationEffect : public nsISupports, public nsWrapperCache {
 
   virtual KeyframeEffect* AsKeyframeEffect() { return nullptr; }
 
-  virtual ElementPropertyTransition* AsTransition() { return nullptr; }
-  virtual const ElementPropertyTransition* AsTransition() const {
-    return nullptr;
-  }
-
   nsISupports* GetParentObject() const { return ToSupports(mDocument); }
 
   bool IsCurrent() const;
@@ -49,9 +41,10 @@ class AnimationEffect : public nsISupports, public nsWrapperCache {
   }
 
   // AnimationEffect interface
-  void GetTiming(EffectTiming& aRetVal) const;
-  void GetComputedTimingAsDict(ComputedEffectTiming& aRetVal) const;
-  void UpdateTiming(const OptionalEffectTiming& aTiming, ErrorResult& aRv);
+  virtual void GetTiming(EffectTiming& aRetVal) const;
+  virtual void GetComputedTimingAsDict(ComputedEffectTiming& aRetVal) const;
+  virtual void UpdateTiming(const OptionalEffectTiming& aTiming,
+                            ErrorResult& aRv);
 
   const TimingParams& SpecifiedTiming() const { return mTiming; }
   void SetSpecifiedTiming(TimingParams&& aTiming);

dom/animation/AnimationEventDispatcher.cpp

@@ -5,6 +5,7 @@
 #include "mozilla/AnimationEventDispatcher.h"
 
 #include "mozilla/EventDispatcher.h"
+#include "nsPresContext.h"
 #include "nsRefreshDriver.h"
 
 namespace mozilla {

dom/animation/AnimationPerformanceWarning.cpp

@@ -66,6 +66,9 @@ bool AnimationPerformanceWarning::ToLocalizedString(
     case Type::HasRenderingObserver:
       key = "CompositorAnimationWarningHasRenderingObserver";
       break;
+    case Type::HasCurrentColor:
+      key = "CompositorAnimationWarningHasCurrentColor";
+      break;
     case Type::None:
       MOZ_ASSERT_UNREACHABLE("Uninitialized type shouldn't be used");
       return false;

dom/animation/AnimationPerformanceWarning.h

@@ -28,6 +28,7 @@ struct AnimationPerformanceWarning {
     TransformIsBlockedByImportantRules,
     OpacityFrameInactive,
     HasRenderingObserver,
+    HasCurrentColor,
   };
 
   explicit AnimationPerformanceWarning(Type aType) : mType(aType) {

dom/animation/AnimationTarget.h

@@ -19,6 +19,8 @@ class Element;
 }  // namespace dom
 
 struct OwningAnimationTarget {
+  OwningAnimationTarget() = default;
+
   OwningAnimationTarget(dom::Element* aElement, PseudoStyleType aType)
       : mElement(aElement), mPseudoType(aType) {}
 
@@ -28,6 +30,8 @@ struct OwningAnimationTarget {
     return mElement == aOther.mElement && mPseudoType == aOther.mPseudoType;
   }
 
+  explicit operator bool() const { return !!mElement; }
+
   // mElement represents the parent element of a pseudo-element, not the
   // generated content element.
   RefPtr<dom::Element> mElement;
@@ -47,6 +51,14 @@ struct NonOwningAnimationTarget {
     return mElement == aOther.mElement && mPseudoType == aOther.mPseudoType;
   }
 
+  NonOwningAnimationTarget& operator=(const OwningAnimationTarget& aOther) {
+    mElement = aOther.mElement;
+    mPseudoType = aOther.mPseudoType;
+    return *this;
+  }
+
+  explicit operator bool() const { return !!mElement; }
+
   // mElement represents the parent element of a pseudo-element, not the
   // generated content element.
   dom::Element* MOZ_NON_OWNING_REF mElement = nullptr;

dom/animation/AnimationUtils.cpp

@@ -4,10 +4,10 @@
 
 #include "AnimationUtils.h"
 
+#include "mozilla/dom/Animation.h"
 #include "mozilla/dom/Document.h"
 #include "mozilla/dom/KeyframeEffect.h"
 #include "mozilla/EffectSet.h"
-#include "mozilla/Preferences.h"
 #include "nsDebug.h"
 #include "nsAtom.h"
 #include "nsIContent.h"
@@ -56,20 +56,6 @@ Document* AnimationUtils::GetDocumentFromGlobal(JSObject* aGlobalObject) {
   return win->GetDoc();
 }
 
-/* static */
-bool AnimationUtils::IsOffscreenThrottlingEnabled() {
-  static bool sOffscreenThrottlingEnabled;
-  static bool sPrefCached = false;
-
-  if (!sPrefCached) {
-    sPrefCached = true;
-    Preferences::AddBoolVarCache(&sOffscreenThrottlingEnabled,
-                                 "dom.animations.offscreen-throttling");
-  }
-
-  return sOffscreenThrottlingEnabled;
-}
-
 /* static */
 bool AnimationUtils::FrameHasAnimatedScale(const nsIFrame* aFrame) {
   EffectSet* effectSet = EffectSet::GetEffectSetForFrame(

dom/animation/AnimationUtils.h

@@ -71,11 +71,6 @@ class AnimationUtils {
    */
   static Document* GetDocumentFromGlobal(JSObject* aGlobalObject);
 
-  /**
-   * Checks if offscreen animation throttling is enabled.
-   */
-  static bool IsOffscreenThrottlingEnabled();
-
   /**
    * Returns true if the given frame has an animated scale.
    */

dom/animation/CSSAnimation.cpp

@@ -0,0 +1,365 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "CSSAnimation.h"
+
+#include "mozilla/AnimationEventDispatcher.h"
+#include "mozilla/dom/CSSAnimationBinding.h"
+#include "mozilla/dom/KeyframeEffectBinding.h"
+#include "mozilla/TimeStamp.h"
+#include "nsPresContext.h"
+
+namespace mozilla {
+namespace dom {
+
+using AnimationPhase = ComputedTiming::AnimationPhase;
+
+JSObject* CSSAnimation::WrapObject(JSContext* aCx,
+                                   JS::Handle<JSObject*> aGivenProto) {
+  return dom::CSSAnimation_Binding::Wrap(aCx, this, aGivenProto);
+}
+
+void CSSAnimation::SetEffect(AnimationEffect* aEffect) {
+  Animation::SetEffect(aEffect);
+
+  AddOverriddenProperties(CSSAnimationProperties::Effect);
+}
+
+void CSSAnimation::SetStartTimeAsDouble(const Nullable<double>& aStartTime) {
+  // Note that we always compare with the paused state since for the purposes
+  // of determining if play control is being overridden or not, we want to
+  // treat the finished state as running.
+  bool wasPaused = PlayState() == AnimationPlayState::Paused;
+
+  Animation::SetStartTimeAsDouble(aStartTime);
+
+  bool isPaused = PlayState() == AnimationPlayState::Paused;
+
+  if (wasPaused != isPaused) {
+    AddOverriddenProperties(CSSAnimationProperties::PlayState);
+  }
+}
+
+mozilla::dom::Promise* CSSAnimation::GetReady(ErrorResult& aRv) {
+  FlushUnanimatedStyle();
+  return Animation::GetReady(aRv);
+}
+
+void CSSAnimation::Reverse(ErrorResult& aRv) {
+  // As with CSSAnimation::SetStartTimeAsDouble, we're really only interested in
+  // the paused state.
+  bool wasPaused = PlayState() == AnimationPlayState::Paused;
+
+  Animation::Reverse(aRv);
+  if (aRv.Failed()) {
+    return;
+  }
+
+  bool isPaused = PlayState() == AnimationPlayState::Paused;
+
+  if (wasPaused != isPaused) {
+    AddOverriddenProperties(CSSAnimationProperties::PlayState);
+  }
+}
+
+AnimationPlayState CSSAnimation::PlayStateFromJS() const {
+  // Flush style to ensure that any properties controlling animation state
+  // (e.g. animation-play-state) are fully updated.
+  FlushUnanimatedStyle();
+  return Animation::PlayStateFromJS();
+}
+
+bool CSSAnimation::PendingFromJS() const {
+  // Flush style since, for example, if the animation-play-state was just
+  // changed its possible we should now be pending.
+  FlushUnanimatedStyle();
+  return Animation::PendingFromJS();
+}
+
+void CSSAnimation::PlayFromJS(ErrorResult& aRv) {
+  // Note that flushing style below might trigger calls to
+  // PlayFromStyle()/PauseFromStyle() on this object.
+  FlushUnanimatedStyle();
+  Animation::PlayFromJS(aRv);
+  if (aRv.Failed()) {
+    return;
+  }
+
+  AddOverriddenProperties(CSSAnimationProperties::PlayState);
+}
+
+void CSSAnimation::PauseFromJS(ErrorResult& aRv) {
+  Animation::PauseFromJS(aRv);
+  if (aRv.Failed()) {
+    return;
+  }
+
+  AddOverriddenProperties(CSSAnimationProperties::PlayState);
+}
+
+void CSSAnimation::PlayFromStyle() {
+  ErrorResult rv;
+  Animation::Play(rv, Animation::LimitBehavior::Continue);
+  // play() should not throw when LimitBehavior is Continue
+  MOZ_ASSERT(!rv.Failed(), "Unexpected exception playing animation");
+}
+
+void CSSAnimation::PauseFromStyle() {
+  ErrorResult rv;
+  Animation::Pause(rv);
+  // pause() should only throw when *all* of the following conditions are true:
+  // - we are in the idle state, and
+  // - we have a negative playback rate, and
+  // - we have an infinitely repeating animation
+  // The first two conditions will never happen under regular style processing
+  // but could happen if an author made modifications to the Animation object
+  // and then updated animation-play-state. It's an unusual case and there's
+  // no obvious way to pass on the exception information so we just silently
+  // fail for now.
+  if (rv.Failed()) {
+    NS_WARNING("Unexpected exception pausing animation - silently failing");
+  }
+}
+
+void CSSAnimation::Tick() {
+  Animation::Tick();
+  QueueEvents();
+}
+
+bool CSSAnimation::HasLowerCompositeOrderThan(
+    const CSSAnimation& aOther) const {
+  MOZ_ASSERT(IsTiedToMarkup() && aOther.IsTiedToMarkup(),
+             "Should only be called for CSS animations that are sorted "
+             "as CSS animations (i.e. tied to CSS markup)");
+
+  // 0. Object-equality case
+  if (&aOther == this) {
+    return false;
+  }
+
+  // 1. Sort by document order
+  if (!mOwningElement.Equals(aOther.mOwningElement)) {
+    return mOwningElement.LessThan(
+        const_cast<CSSAnimation*>(this)->CachedChildIndexRef(),
+        aOther.mOwningElement,
+        const_cast<CSSAnimation*>(&aOther)->CachedChildIndexRef());
+  }
+
+  // 2. (Same element and pseudo): Sort by position in animation-name
+  return mAnimationIndex < aOther.mAnimationIndex;
+}
+
+void CSSAnimation::QueueEvents(const StickyTimeDuration& aActiveTime) {
+  // If the animation is pending, we ignore animation events until we finish
+  // pending.
+  if (mPendingState != PendingState::NotPending) {
+    return;
+  }
+
+  // CSS animations dispatch events at their owning element. This allows
+  // script to repurpose a CSS animation to target a different element,
+  // to use a group effect (which has no obvious "target element"), or
+  // to remove the animation effect altogether whilst still getting
+  // animation events.
+  //
+  // It does mean, however, that for a CSS animation that has no owning
+  // element (e.g. it was created using the CSSAnimation constructor or
+  // disassociated from CSS) no events are fired. If it becomes desirable
+  // for these animations to still fire events we should spec the concept
+  // of the "original owning element" or "event target" and allow script
+  // to set it when creating a CSSAnimation object.
+  if (!mOwningElement.IsSet()) {
+    return;
+  }
+
+  nsPresContext* presContext = mOwningElement.GetPresContext();
+  if (!presContext) {
+    return;
+  }
+
+  uint64_t currentIteration = 0;
+  ComputedTiming::AnimationPhase currentPhase;
+  StickyTimeDuration intervalStartTime;
+  StickyTimeDuration intervalEndTime;
+  StickyTimeDuration iterationStartTime;
+
+  if (!mEffect) {
+    currentPhase =
+        GetAnimationPhaseWithoutEffect<ComputedTiming::AnimationPhase>(*this);
+    if (currentPhase == mPreviousPhase) {
+      return;
+    }
+  } else {
+    ComputedTiming computedTiming = mEffect->GetComputedTiming();
+    currentPhase = computedTiming.mPhase;
+    currentIteration = computedTiming.mCurrentIteration;
+    if (currentPhase == mPreviousPhase &&
+        currentIteration == mPreviousIteration) {
+      return;
+    }
+    intervalStartTime = IntervalStartTime(computedTiming.mActiveDuration);
+    intervalEndTime = IntervalEndTime(computedTiming.mActiveDuration);
+
+    uint64_t iterationBoundary = mPreviousIteration > currentIteration
+                                     ? currentIteration + 1
+                                     : currentIteration;
+    iterationStartTime = computedTiming.mDuration.MultDouble(
+        (iterationBoundary - computedTiming.mIterationStart));
+  }
+
+  TimeStamp startTimeStamp = ElapsedTimeToTimeStamp(intervalStartTime);
+  TimeStamp endTimeStamp = ElapsedTimeToTimeStamp(intervalEndTime);
+  TimeStamp iterationTimeStamp = ElapsedTimeToTimeStamp(iterationStartTime);
+
+  AutoTArray<AnimationEventInfo, 2> events;
+
+  auto appendAnimationEvent = [&](EventMessage aMessage,
+                                  const StickyTimeDuration& aElapsedTime,
+                                  const TimeStamp& aScheduledEventTimeStamp) {
+    double elapsedTime = aElapsedTime.ToSeconds();
+    if (aMessage == eAnimationCancel) {
+      // 0 is an inappropriate value for this callsite. What we need to do is
+      // use a single random value for all increasing times reportable.
+      // That is to say, whenever elapsedTime goes negative (because an
+      // animation restarts, something rewinds the animation, or otherwise)
+      // a new random value for the mix-in must be generated.
+      elapsedTime = nsRFPService::ReduceTimePrecisionAsSecs(
+          elapsedTime, 0, TimerPrecisionType::RFPOnly);
+    }
+    events.AppendElement(
+        AnimationEventInfo(mAnimationName, mOwningElement.Target(), aMessage,
+                           elapsedTime, aScheduledEventTimeStamp, this));
+  };
+
+  // Handle cancel event first
+  if ((mPreviousPhase != AnimationPhase::Idle &&
+       mPreviousPhase != AnimationPhase::After) &&
+      currentPhase == AnimationPhase::Idle) {
+    appendAnimationEvent(eAnimationCancel, aActiveTime,
+                         GetTimelineCurrentTimeAsTimeStamp());
+  }
+
+  switch (mPreviousPhase) {
+    case AnimationPhase::Idle:
+    case AnimationPhase::Before:
+      if (currentPhase == AnimationPhase::Active) {
+        appendAnimationEvent(eAnimationStart, intervalStartTime,
+                             startTimeStamp);
+      } else if (currentPhase == AnimationPhase::After) {
+        appendAnimationEvent(eAnimationStart, intervalStartTime,
+                             startTimeStamp);
+        appendAnimationEvent(eAnimationEnd, intervalEndTime, endTimeStamp);
+      }
+      break;
+    case AnimationPhase::Active:
+      if (currentPhase == AnimationPhase::Before) {
+        appendAnimationEvent(eAnimationEnd, intervalStartTime, startTimeStamp);
+      } else if (currentPhase == AnimationPhase::Active) {
+        // The currentIteration must have changed or element we would have
+        // returned early above.
+        MOZ_ASSERT(currentIteration != mPreviousIteration);
+        appendAnimationEvent(eAnimationIteration, iterationStartTime,
+                             iterationTimeStamp);
+      } else if (currentPhase == AnimationPhase::After) {
+        appendAnimationEvent(eAnimationEnd, intervalEndTime, endTimeStamp);
+      }
+      break;
+    case AnimationPhase::After:
+      if (currentPhase == AnimationPhase::Before) {
+        appendAnimationEvent(eAnimationStart, intervalEndTime, startTimeStamp);
+        appendAnimationEvent(eAnimationEnd, intervalStartTime, endTimeStamp);
+      } else if (currentPhase == AnimationPhase::Active) {
+        appendAnimationEvent(eAnimationStart, intervalEndTime, endTimeStamp);
+      }
+      break;
+  }
+  mPreviousPhase = currentPhase;
+  mPreviousIteration = currentIteration;
+
+  if (!events.IsEmpty()) {
+    presContext->AnimationEventDispatcher()->QueueEvents(std::move(events));
+  }
+}
+
+void CSSAnimation::UpdateTiming(SeekFlag aSeekFlag,
+                                SyncNotifyFlag aSyncNotifyFlag) {
+  if (mNeedsNewAnimationIndexWhenRun &&
+      PlayState() != AnimationPlayState::Idle) {
+    mAnimationIndex = sNextAnimationIndex++;
+    mNeedsNewAnimationIndexWhenRun = false;
+  }
+
+  Animation::UpdateTiming(aSeekFlag, aSyncNotifyFlag);
+}
+
+/////////////////////// CSSAnimationKeyframeEffect ////////////////////////
+
+void CSSAnimationKeyframeEffect::GetTiming(EffectTiming& aRetVal) const {
+  MaybeFlushUnanimatedStyle();
+  KeyframeEffect::GetTiming(aRetVal);
+}
+
+void CSSAnimationKeyframeEffect::GetComputedTimingAsDict(
+    ComputedEffectTiming& aRetVal) const {
+  MaybeFlushUnanimatedStyle();
+  KeyframeEffect::GetComputedTimingAsDict(aRetVal);
+}
+
+void CSSAnimationKeyframeEffect::UpdateTiming(
+    const OptionalEffectTiming& aTiming, ErrorResult& aRv) {
+  KeyframeEffect::UpdateTiming(aTiming, aRv);
+
+  if (aRv.Failed()) {
+    return;
+  }
+
+  if (CSSAnimation* cssAnimation = GetOwningCSSAnimation()) {
+    CSSAnimationProperties updatedProperties = CSSAnimationProperties::None;
+    if (aTiming.mDuration.WasPassed()) {
+      updatedProperties |= CSSAnimationProperties::Duration;
+    }
+    if (aTiming.mIterations.WasPassed()) {
+      updatedProperties |= CSSAnimationProperties::IterationCount;
+    }
+    if (aTiming.mDirection.WasPassed()) {
+      updatedProperties |= CSSAnimationProperties::Direction;
+    }
+    if (aTiming.mDelay.WasPassed()) {
+      updatedProperties |= CSSAnimationProperties::Delay;
+    }
+    if (aTiming.mFill.WasPassed()) {
+      updatedProperties |= CSSAnimationProperties::FillMode;
+    }
+
+    cssAnimation->AddOverriddenProperties(updatedProperties);
+  }
+}
+
+void CSSAnimationKeyframeEffect::SetKeyframes(JSContext* aContext,
+                                              JS::Handle<JSObject*> aKeyframes,
+                                              ErrorResult& aRv) {
+  KeyframeEffect::SetKeyframes(aContext, aKeyframes, aRv);
+
+  if (aRv.Failed()) {
+    return;
+  }
+
+  if (CSSAnimation* cssAnimation = GetOwningCSSAnimation()) {
+    cssAnimation->AddOverriddenProperties(CSSAnimationProperties::Keyframes);
+  }
+}
+
+void CSSAnimationKeyframeEffect::MaybeFlushUnanimatedStyle() const {
+  if (!GetOwningCSSAnimation()) {
+    return;
+  }
+
+  if (dom::Document* doc = GetRenderedDocument()) {
+    doc->FlushPendingNotifications(
+        ChangesToFlush(FlushType::Style, false /* flush animations */));
+  }
+}
+
+}  // namespace dom
+}  // namespace mozilla

dom/animation/CSSAnimation.h

@@ -0,0 +1,247 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_CSSAnimation_h
+#define mozilla_dom_CSSAnimation_h
+
+#include "mozilla/dom/Animation.h"
+#include "mozilla/dom/KeyframeEffect.h"
+#include "mozilla/dom/MutationObservers.h"
+#include "mozilla/StyleAnimationValue.h"
+#include "AnimationCommon.h"
+
+namespace mozilla {
+// Properties of CSS Animations that can be overridden by the Web Animations API
+// in a manner that means we should ignore subsequent changes to markup for that
+// property.
+enum class CSSAnimationProperties {
+  None = 0,
+  Keyframes = 1 << 0,
+  Duration = 1 << 1,
+  IterationCount = 1 << 2,
+  Direction = 1 << 3,
+  Delay = 1 << 4,
+  FillMode = 1 << 5,
+  Effect = Keyframes | Duration | IterationCount | Direction | Delay | FillMode,
+  PlayState = 1 << 6,
+};
+MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(CSSAnimationProperties)
+
+namespace dom {
+
+class CSSAnimation final : public Animation {
+ public:
+  explicit CSSAnimation(nsIGlobalObject* aGlobal, nsAtom* aAnimationName)
+      : dom::Animation(aGlobal),
+        mAnimationName(aAnimationName),
+        mNeedsNewAnimationIndexWhenRun(false),
+        mPreviousPhase(ComputedTiming::AnimationPhase::Idle),
+        mPreviousIteration(0) {
+    // We might need to drop this assertion once we add a script-accessible
+    // constructor but for animations generated from CSS markup the
+    // animation-name should never be empty.
+    MOZ_ASSERT(mAnimationName != nsGkAtoms::_empty,
+               "animation-name should not be 'none'");
+  }
+
+  JSObject* WrapObject(JSContext* aCx,
+                       JS::Handle<JSObject*> aGivenProto) override;
+
+  CSSAnimation* AsCSSAnimation() override { return this; }
+  const CSSAnimation* AsCSSAnimation() const override { return this; }
+
+  // CSSAnimation interface
+  void GetAnimationName(nsString& aRetVal) const {
+    mAnimationName->ToString(aRetVal);
+  }
+
+  nsAtom* AnimationName() const { return mAnimationName; }
+
+  // Animation interface overrides
+  void SetEffect(AnimationEffect* aEffect) override;
+  void SetStartTimeAsDouble(const Nullable<double>& aStartTime) override;
+  Promise* GetReady(ErrorResult& aRv) override;
+  void Reverse(ErrorResult& aRv) override;
+
+  // NOTE: tabbrowser.xml currently relies on the fact that reading the
+  // currentTime of a CSSAnimation does *not* flush style (whereas reading the
+  // playState does). If CSS Animations 2 specifies that reading currentTime
+  // also flushes style we will need to find another way to detect canceled
+  // animations in tabbrowser.xml. On the other hand, if CSS Animations 2
+  // specifies that reading playState does *not* flush style (and we drop the
+  // following override), then we should update tabbrowser.xml to check
+  // the playState instead.
+  AnimationPlayState PlayStateFromJS() const override;
+  bool PendingFromJS() const override;
+  void PlayFromJS(ErrorResult& aRv) override;
+  void PauseFromJS(ErrorResult& aRv) override;
+
+  void PlayFromStyle();
+  void PauseFromStyle();
+  void CancelFromStyle(PostRestyleMode aPostRestyle) {
+    // When an animation is disassociated with style it enters an odd state
+    // where its composite order is undefined until it first transitions
+    // out of the idle state.
+    //
+    // Even if the composite order isn't defined we don't want it to be random
+    // in case we need to determine the order to dispatch events associated
+    // with an animation in this state. To solve this we treat the animation as
+    // if it had been added to the end of the global animation list so that
+    // its sort order is defined. We'll update this index again once the
+    // animation leaves the idle state.
+    mAnimationIndex = sNextAnimationIndex++;
+    mNeedsNewAnimationIndexWhenRun = true;
+
+    Animation::Cancel(aPostRestyle);
+
+    // We need to do this *after* calling Cancel() since
+    // Cancel() might synchronously trigger a cancel event for which
+    // we need an owning element to target the event at.
+    mOwningElement = OwningElementRef();
+  }
+
+  void Tick() override;
+  void QueueEvents(
+      const StickyTimeDuration& aActiveTime = StickyTimeDuration());
+
+  bool HasLowerCompositeOrderThan(const CSSAnimation& aOther) const;
+
+  void SetAnimationIndex(uint64_t aIndex) {
+    MOZ_ASSERT(IsTiedToMarkup());
+    if (IsRelevant() && mAnimationIndex != aIndex) {
+      MutationObservers::NotifyAnimationChanged(this);
+      PostUpdate();
+    }
+    mAnimationIndex = aIndex;
+  }
+
+  // Sets the owning element which is used for determining the composite
+  // order of CSSAnimation objects generated from CSS markup.
+  //
+  // @see mOwningElement
+  void SetOwningElement(const OwningElementRef& aElement) {
+    mOwningElement = aElement;
+  }
+  // True for animations that are generated from CSS markup and continue to
+  // reflect changes to that markup.
+  bool IsTiedToMarkup() const { return mOwningElement.IsSet(); }
+
+  void MaybeQueueCancelEvent(const StickyTimeDuration& aActiveTime) override {
+    QueueEvents(aActiveTime);
+  }
+
+  CSSAnimationProperties GetOverriddenProperties() const {
+    return mOverriddenProperties;
+  }
+  void AddOverriddenProperties(CSSAnimationProperties aProperties) {
+    mOverriddenProperties |= aProperties;
+  }
+
+ protected:
+  virtual ~CSSAnimation() {
+    MOZ_ASSERT(!mOwningElement.IsSet(),
+               "Owning element should be cleared "
+               "before a CSS animation is destroyed");
+  }
+
+  // Animation overrides
+  void UpdateTiming(SeekFlag aSeekFlag,
+                    SyncNotifyFlag aSyncNotifyFlag) override;
+
+  // Returns the duration from the start of the animation's source effect's
+  // active interval to the point where the animation actually begins playback.
+  // This is zero unless the animation's source effect has a negative delay in
+  // which case it is the absolute value of that delay.
+  // This is used for setting the elapsedTime member of CSS AnimationEvents.
+  TimeDuration InitialAdvance() const {
+    return mEffect ? std::max(TimeDuration(),
+                              mEffect->SpecifiedTiming().Delay() * -1)
+                   : TimeDuration();
+  }
+
+  RefPtr<nsAtom> mAnimationName;
+
+  // The (pseudo-)element whose computed animation-name refers to this
+  // animation (if any).
+  //
+  // This is used for determining the relative composite order of animations
+  // generated from CSS markup.
+  //
+  // Typically this will be the same as the target element of the keyframe
+  // effect associated with this animation. However, it can differ in the
+  // following circumstances:
+  //
+  // a) If script removes or replaces the effect of this animation,
+  // b) If this animation is cancelled (e.g. by updating the
+  //    animation-name property or removing the owning element from the
+  //    document),
+  // c) If this object is generated from script using the CSSAnimation
+  //    constructor.
+  //
+  // For (b) and (c) the owning element will return !IsSet().
+  OwningElementRef mOwningElement;
+
+  // When true, indicates that when this animation next leaves the idle state,
+  // its animation index should be updated.
+  bool mNeedsNewAnimationIndexWhenRun;
+
+  // Phase and current iteration from the previous time we queued events.
+  // This is used to determine what new events to dispatch.
+  ComputedTiming::AnimationPhase mPreviousPhase;
+  uint64_t mPreviousIteration;
+
+  // Properties that would normally be defined by the cascade but which have
+  // since been explicitly set via the Web Animations API.
+  CSSAnimationProperties mOverriddenProperties = CSSAnimationProperties::None;
+};
+
+// A subclass of KeyframeEffect that reports when specific properties have been
+// overridden via the Web Animations API.
+class CSSAnimationKeyframeEffect : public KeyframeEffect {
+ public:
+  CSSAnimationKeyframeEffect(Document* aDocument,
+                             OwningAnimationTarget&& aTarget,
+                             TimingParams&& aTiming,
+                             const KeyframeEffectParams& aOptions)
+      : KeyframeEffect(aDocument, std::move(aTarget), std::move(aTiming),
+                       aOptions) {}
+
+  void GetTiming(EffectTiming& aRetVal) const override;
+  void GetComputedTimingAsDict(ComputedEffectTiming& aRetVal) const override;
+  void UpdateTiming(const OptionalEffectTiming& aTiming,
+                    ErrorResult& aRv) override;
+  void SetKeyframes(JSContext* aContext, JS::Handle<JSObject*> aKeyframes,
+                    ErrorResult& aRv) override;
+
+ private:
+  CSSAnimation* GetOwningCSSAnimation() {
+    return mAnimation ? mAnimation->AsCSSAnimation() : nullptr;
+  }
+  const CSSAnimation* GetOwningCSSAnimation() const {
+    return mAnimation ? mAnimation->AsCSSAnimation() : nullptr;
+  }
+
+  // Flushes styles if our owning animation is a CSSAnimation
+  void MaybeFlushUnanimatedStyle() const;
+};
+
+}  // namespace dom
+
+template <>
+struct AnimationTypeTraits<dom::CSSAnimation> {
+  static nsAtom* ElementPropertyAtom() { return nsGkAtoms::animationsProperty; }
+  static nsAtom* BeforePropertyAtom() {
+    return nsGkAtoms::animationsOfBeforeProperty;
+  }
+  static nsAtom* AfterPropertyAtom() {
+    return nsGkAtoms::animationsOfAfterProperty;
+  }
+  static nsAtom* MarkerPropertyAtom() {
+    return nsGkAtoms::animationsOfMarkerProperty;
+  }
+};
+
+}  // namespace mozilla
+
+#endif  // mozilla_dom_CSSAnimation_h

dom/animation/CSSPseudoElement.cpp

@@ -29,7 +29,7 @@ CSSPseudoElement::CSSPseudoElement(dom::Element* aElement,
 CSSPseudoElement::~CSSPseudoElement() {
   // Element might have been unlinked already, so we have to do null check.
   if (mOriginatingElement) {
-    mOriginatingElement->DeleteProperty(
+    mOriginatingElement->RemoveProperty(
         GetCSSPseudoElementPropertyAtom(mPseudoType));
   }
 }
@@ -43,31 +43,6 @@ JSObject* CSSPseudoElement::WrapObject(JSContext* aCx,
   return CSSPseudoElement_Binding::Wrap(aCx, this, aGivenProto);
 }
 
-void CSSPseudoElement::GetAnimations(const GetAnimationsOptions& aOptions,
-                                     nsTArray<RefPtr<Animation>>& aRetVal) {
-  Document* doc = mOriginatingElement->GetComposedDoc();
-  if (doc) {
-    // We don't need to explicitly flush throttled animations here, since
-    // updating the animation style of (pseudo-)elements will never affect the
-    // set of running animations and it's only the set of running animations
-    // that is important here.
-    doc->FlushPendingNotifications(
-        ChangesToFlush(FlushType::Style, false /* flush animations */));
-  }
-
-  Element::GetAnimationsUnsorted(mOriginatingElement, mPseudoType, aRetVal);
-  aRetVal.Sort(AnimationPtrComparator<RefPtr<Animation>>());
-}
-
-already_AddRefed<Animation> CSSPseudoElement::Animate(
-    JSContext* aContext, JS::Handle<JSObject*> aKeyframes,
-    const UnrestrictedDoubleOrKeyframeAnimationOptions& aOptions,
-    ErrorResult& aError) {
-  Nullable<ElementOrCSSPseudoElement> target;
-  target.SetValue().SetAsCSSPseudoElement() = this;
-  return Element::Animate(target, aContext, aKeyframes, aOptions, aError);
-}
-
 /* static */
 already_AddRefed<CSSPseudoElement> CSSPseudoElement::GetCSSPseudoElement(
     dom::Element* aElement, PseudoStyleType aType) {

dom/animation/CSSPseudoElement.h

@@ -52,13 +52,6 @@ class CSSPseudoElement final : public nsWrapperCache {
     return retVal.forget();
   }
 
-  void GetAnimations(const GetAnimationsOptions& aOptions,
-                     nsTArray<RefPtr<Animation>>& aRetVal);
-  already_AddRefed<Animation> Animate(
-      JSContext* aContext, JS::Handle<JSObject*> aKeyframes,
-      const UnrestrictedDoubleOrKeyframeAnimationOptions& aOptions,
-      ErrorResult& aError);
-
   // Given an element:pseudoType pair, returns the CSSPseudoElement stored as a
   // property on |aElement|. If there is no CSSPseudoElement for the specified
   // pseudo-type on element, a new CSSPseudoElement will be created and stored

dom/animation/CSSTransition.cpp

@@ -0,0 +1,336 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "CSSTransition.h"
+
+#include "mozilla/AnimationEventDispatcher.h"
+#include "mozilla/dom/CSSTransitionBinding.h"
+#include "mozilla/dom/KeyframeEffectBinding.h"
+#include "mozilla/dom/KeyframeEffect.h"
+#include "mozilla/TimeStamp.h"
+#include "nsPresContext.h"
+
+namespace mozilla {
+namespace dom {
+
+JSObject* CSSTransition::WrapObject(JSContext* aCx,
+                                    JS::Handle<JSObject*> aGivenProto) {
+  return dom::CSSTransition_Binding::Wrap(aCx, this, aGivenProto);
+}
+
+void CSSTransition::GetTransitionProperty(nsString& aRetVal) const {
+  MOZ_ASSERT(eCSSProperty_UNKNOWN != mTransitionProperty,
+             "Transition Property should be initialized");
+  aRetVal =
+      NS_ConvertUTF8toUTF16(nsCSSProps::GetStringValue(mTransitionProperty));
+}
+
+AnimationPlayState CSSTransition::PlayStateFromJS() const {
+  FlushUnanimatedStyle();
+  return Animation::PlayStateFromJS();
+}
+
+bool CSSTransition::PendingFromJS() const {
+  // Transitions don't become pending again after they start running but, if
+  // while the transition is still pending, style is updated in such a way
+  // that the transition will be canceled, we need to report false here.
+  // Hence we need to flush, but only when we're pending.
+  if (Pending()) {
+    FlushUnanimatedStyle();
+  }
+  return Animation::PendingFromJS();
+}
+
+void CSSTransition::PlayFromJS(ErrorResult& aRv) {
+  FlushUnanimatedStyle();
+  Animation::PlayFromJS(aRv);
+}
+
+void CSSTransition::UpdateTiming(SeekFlag aSeekFlag,
+                                 SyncNotifyFlag aSyncNotifyFlag) {
+  if (mNeedsNewAnimationIndexWhenRun &&
+      PlayState() != AnimationPlayState::Idle) {
+    mAnimationIndex = sNextAnimationIndex++;
+    mNeedsNewAnimationIndexWhenRun = false;
+  }
+
+  Animation::UpdateTiming(aSeekFlag, aSyncNotifyFlag);
+}
+
+void CSSTransition::QueueEvents(const StickyTimeDuration& aActiveTime) {
+  if (!mOwningElement.IsSet()) {
+    return;
+  }
+
+  nsPresContext* presContext = mOwningElement.GetPresContext();
+  if (!presContext) {
+    return;
+  }
+
+  static constexpr StickyTimeDuration zeroDuration = StickyTimeDuration();
+
+  TransitionPhase currentPhase;
+  StickyTimeDuration intervalStartTime;
+  StickyTimeDuration intervalEndTime;
+
+  if (!mEffect) {
+    currentPhase = GetAnimationPhaseWithoutEffect<TransitionPhase>(*this);
+  } else {
+    ComputedTiming computedTiming = mEffect->GetComputedTiming();
+
+    currentPhase = static_cast<TransitionPhase>(computedTiming.mPhase);
+    intervalStartTime = IntervalStartTime(computedTiming.mActiveDuration);
+    intervalEndTime = IntervalEndTime(computedTiming.mActiveDuration);
+  }
+
+  if (mPendingState != PendingState::NotPending &&
+      (mPreviousTransitionPhase == TransitionPhase::Idle ||
+       mPreviousTransitionPhase == TransitionPhase::Pending)) {
+    currentPhase = TransitionPhase::Pending;
+  }
+
+  if (currentPhase == mPreviousTransitionPhase) {
+    return;
+  }
+
+  // TimeStamps to use for ordering the events when they are dispatched. We
+  // use a TimeStamp so we can compare events produced by different elements,
+  // perhaps even with different timelines.
+  // The zero timestamp is for transitionrun events where we ignore the delay
+  // for the purpose of ordering events.
+  TimeStamp zeroTimeStamp = AnimationTimeToTimeStamp(zeroDuration);
+  TimeStamp startTimeStamp = ElapsedTimeToTimeStamp(intervalStartTime);
+  TimeStamp endTimeStamp = ElapsedTimeToTimeStamp(intervalEndTime);
+
+  AutoTArray<AnimationEventInfo, 3> events;
+
+  auto appendTransitionEvent = [&](EventMessage aMessage,
+                                   const StickyTimeDuration& aElapsedTime,
+                                   const TimeStamp& aScheduledEventTimeStamp) {
+    double elapsedTime = aElapsedTime.ToSeconds();
+    if (aMessage == eTransitionCancel) {
+      // 0 is an inappropriate value for this callsite. What we need to do is
+      // use a single random value for all increasing times reportable.
+      // That is to say, whenever elapsedTime goes negative (because an
+      // animation restarts, something rewinds the animation, or otherwise)
+      // a new random value for the mix-in must be generated.
+      elapsedTime = nsRFPService::ReduceTimePrecisionAsSecs(
+          elapsedTime, 0, TimerPrecisionType::RFPOnly);
+    }
+    events.AppendElement(AnimationEventInfo(
+        TransitionProperty(), mOwningElement.Target(), aMessage, elapsedTime,
+        aScheduledEventTimeStamp, this));
+  };
+
+  // Handle cancel events first
+  if ((mPreviousTransitionPhase != TransitionPhase::Idle &&
+       mPreviousTransitionPhase != TransitionPhase::After) &&
+      currentPhase == TransitionPhase::Idle) {
+    appendTransitionEvent(eTransitionCancel, aActiveTime,
+                          GetTimelineCurrentTimeAsTimeStamp());
+  }
+
+  // All other events
+  switch (mPreviousTransitionPhase) {
+    case TransitionPhase::Idle:
+      if (currentPhase == TransitionPhase::Pending ||
+          currentPhase == TransitionPhase::Before) {
+        appendTransitionEvent(eTransitionRun, intervalStartTime, zeroTimeStamp);
+      } else if (currentPhase == TransitionPhase::Active) {
+        appendTransitionEvent(eTransitionRun, intervalStartTime, zeroTimeStamp);
+        appendTransitionEvent(eTransitionStart, intervalStartTime,
+                              startTimeStamp);
+      } else if (currentPhase == TransitionPhase::After) {
+        appendTransitionEvent(eTransitionRun, intervalStartTime, zeroTimeStamp);
+        appendTransitionEvent(eTransitionStart, intervalStartTime,
+                              startTimeStamp);
+        appendTransitionEvent(eTransitionEnd, intervalEndTime, endTimeStamp);
+      }
+      break;
+
+    case TransitionPhase::Pending:
+    case TransitionPhase::Before:
+      if (currentPhase == TransitionPhase::Active) {
+        appendTransitionEvent(eTransitionStart, intervalStartTime,
+                              startTimeStamp);
+      } else if (currentPhase == TransitionPhase::After) {
+        appendTransitionEvent(eTransitionStart, intervalStartTime,
+                              startTimeStamp);
+        appendTransitionEvent(eTransitionEnd, intervalEndTime, endTimeStamp);
+      }
+      break;
+
+    case TransitionPhase::Active:
+      if (currentPhase == TransitionPhase::After) {
+        appendTransitionEvent(eTransitionEnd, intervalEndTime, endTimeStamp);
+      } else if (currentPhase == TransitionPhase::Before) {
+        appendTransitionEvent(eTransitionEnd, intervalStartTime,
+                              startTimeStamp);
+      }
+      break;
+
+    case TransitionPhase::After:
+      if (currentPhase == TransitionPhase::Active) {
+        appendTransitionEvent(eTransitionStart, intervalEndTime,
+                              startTimeStamp);
+      } else if (currentPhase == TransitionPhase::Before) {
+        appendTransitionEvent(eTransitionStart, intervalEndTime,
+                              startTimeStamp);
+        appendTransitionEvent(eTransitionEnd, intervalStartTime, endTimeStamp);
+      }
+      break;
+  }
+  mPreviousTransitionPhase = currentPhase;
+
+  if (!events.IsEmpty()) {
+    presContext->AnimationEventDispatcher()->QueueEvents(std::move(events));
+  }
+}
+
+void CSSTransition::Tick() {
+  Animation::Tick();
+  QueueEvents();
+}
+
+nsCSSPropertyID CSSTransition::TransitionProperty() const {
+  MOZ_ASSERT(eCSSProperty_UNKNOWN != mTransitionProperty,
+             "Transition property should be initialized");
+  return mTransitionProperty;
+}
+
+AnimationValue CSSTransition::ToValue() const {
+  MOZ_ASSERT(!mTransitionToValue.IsNull(),
+             "Transition ToValue should be initialized");
+  return mTransitionToValue;
+}
+
+bool CSSTransition::HasLowerCompositeOrderThan(
+    const CSSTransition& aOther) const {
+  MOZ_ASSERT(IsTiedToMarkup() && aOther.IsTiedToMarkup(),
+             "Should only be called for CSS transitions that are sorted "
+             "as CSS transitions (i.e. tied to CSS markup)");
+
+  // 0. Object-equality case
+  if (&aOther == this) {
+    return false;
+  }
+
+  // 1. Sort by document order
+  if (!mOwningElement.Equals(aOther.mOwningElement)) {
+    return mOwningElement.LessThan(
+        const_cast<CSSTransition*>(this)->CachedChildIndexRef(),
+        aOther.mOwningElement,
+        const_cast<CSSTransition*>(&aOther)->CachedChildIndexRef());
+  }
+
+  // 2. (Same element and pseudo): Sort by transition generation
+  if (mAnimationIndex != aOther.mAnimationIndex) {
+    return mAnimationIndex < aOther.mAnimationIndex;
+  }
+
+  // 3. (Same transition generation): Sort by transition property
+  return nsCSSProps::GetStringValue(TransitionProperty()) <
+         nsCSSProps::GetStringValue(aOther.TransitionProperty());
+}
+
+/* static */
+Nullable<TimeDuration> CSSTransition::GetCurrentTimeAt(
+    const AnimationTimeline& aTimeline, const TimeStamp& aBaseTime,
+    const TimeDuration& aStartTime, double aPlaybackRate) {
+  Nullable<TimeDuration> result;
+
+  Nullable<TimeDuration> timelineTime = aTimeline.ToTimelineTime(aBaseTime);
+  if (!timelineTime.IsNull()) {
+    result.SetValue(
+        (timelineTime.Value() - aStartTime).MultDouble(aPlaybackRate));
+  }
+
+  return result;
+}
+
+double CSSTransition::CurrentValuePortion() const {
+  if (!GetEffect()) {
+    return 0.0;
+  }
+
+  // Transitions use a fill mode of 'backwards' so GetComputedTiming will
+  // never return a null time progress due to being *before* the animation
+  // interval. However, it might be possible that we're behind on flushing
+  // causing us to get called *after* the animation interval. So, just in
+  // case, we override the fill mode to 'both' to ensure the progress
+  // is never null.
+  TimingParams timingToUse = GetEffect()->SpecifiedTiming();
+  timingToUse.SetFill(dom::FillMode::Both);
+  ComputedTiming computedTiming = GetEffect()->GetComputedTiming(&timingToUse);
+
+  if (computedTiming.mProgress.IsNull()) {
+    return 0.0;
+  }
+
+  // 'transition-timing-function' corresponds to the effect timing while
+  // the transition keyframes have a linear timing function so we can ignore
+  // them for the purposes of calculating the value portion.
+  return computedTiming.mProgress.Value();
+}
+
+void CSSTransition::UpdateStartValueFromReplacedTransition() {
+  MOZ_ASSERT(mEffect && mEffect->AsKeyframeEffect() &&
+                 mEffect->AsKeyframeEffect()->HasAnimationOfPropertySet(
+                     nsCSSPropertyIDSet::CompositorAnimatables()),
+             "Should be called for compositor-runnable transitions");
+
+  MOZ_ASSERT(mTimeline,
+             "Should have a timeline if we are replacing transition start "
+             "values");
+
+  if (!mReplacedTransition) {
+    return;
+  }
+
+  ComputedTiming computedTiming = AnimationEffect::GetComputedTimingAt(
+      CSSTransition::GetCurrentTimeAt(*mTimeline, TimeStamp::Now(),
+                                      mReplacedTransition->mStartTime,
+                                      mReplacedTransition->mPlaybackRate),
+      mReplacedTransition->mTiming, mReplacedTransition->mPlaybackRate);
+
+  if (!computedTiming.mProgress.IsNull()) {
+    double valuePosition = ComputedTimingFunction::GetPortion(
+        mReplacedTransition->mTimingFunction, computedTiming.mProgress.Value(),
+        computedTiming.mBeforeFlag);
+
+    const AnimationValue& replacedFrom = mReplacedTransition->mFromValue;
+    const AnimationValue& replacedTo = mReplacedTransition->mToValue;
+    AnimationValue startValue;
+    startValue.mServo =
+        Servo_AnimationValues_Interpolate(replacedFrom.mServo,
+                                          replacedTo.mServo, valuePosition)
+            .Consume();
+
+    mEffect->AsKeyframeEffect()->ReplaceTransitionStartValue(
+        std::move(startValue));
+  }
+
+  mReplacedTransition.reset();
+}
+
+void CSSTransition::SetEffectFromStyle(dom::AnimationEffect* aEffect) {
+  Animation::SetEffectNoUpdate(aEffect);
+
+  // Initialize transition property and to value.
+  //
+  // Typically this should only be called with a KeyframeEffect representing
+  // a simple transition, but just to be sure we check the effect has the
+  // expected shape first.
+  const KeyframeEffect* keyframeEffect = aEffect->AsKeyframeEffect();
+  if (MOZ_LIKELY(keyframeEffect && keyframeEffect->Properties().Length() == 1 &&
+                 keyframeEffect->Properties()[0].mSegments.Length() == 1)) {
+    mTransitionProperty = keyframeEffect->Properties()[0].mProperty;
+    mTransitionToValue = keyframeEffect->Properties()[0].mSegments[0].mToValue;
+  } else {
+    MOZ_ASSERT_UNREACHABLE("Transition effect has unexpected shape");
+  }
+}
+
+}  // namespace dom
+}  // namespace mozilla

dom/animation/CSSTransition.h

@@ -0,0 +1,243 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_CSSTransition_h
+#define mozilla_dom_CSSTransition_h
+
+#include "mozilla/dom/Animation.h"
+#include "mozilla/StyleAnimationValue.h"
+#include "AnimationCommon.h"
+
+class nsIGlobalObject;
+
+namespace mozilla {
+namespace dom {
+
+class CSSTransition final : public Animation {
+ public:
+  explicit CSSTransition(nsIGlobalObject* aGlobal)
+      : dom::Animation(aGlobal),
+        mPreviousTransitionPhase(TransitionPhase::Idle),
+        mNeedsNewAnimationIndexWhenRun(false),
+        mTransitionProperty(eCSSProperty_UNKNOWN) {}
+
+  JSObject* WrapObject(JSContext* aCx,
+                       JS::Handle<JSObject*> aGivenProto) override;
+
+  CSSTransition* AsCSSTransition() override { return this; }
+  const CSSTransition* AsCSSTransition() const override { return this; }
+
+  // CSSTransition interface
+  void GetTransitionProperty(nsString& aRetVal) const;
+
+  // Animation interface overrides
+  AnimationPlayState PlayStateFromJS() const override;
+  bool PendingFromJS() const override;
+  void PlayFromJS(ErrorResult& aRv) override;
+
+  // A variant of Play() that avoids posting style updates since this method
+  // is expected to be called whilst already updating style.
+  void PlayFromStyle() {
+    ErrorResult rv;
+    PlayNoUpdate(rv, Animation::LimitBehavior::Continue);
+    // play() should not throw when LimitBehavior is Continue
+    MOZ_ASSERT(!rv.Failed(), "Unexpected exception playing transition");
+  }
+
+  void CancelFromStyle(PostRestyleMode aPostRestyle) {
+    // The animation index to use for compositing will be established when
+    // this transition next transitions out of the idle state but we still
+    // update it now so that the sort order of this transition remains
+    // defined until that moment.
+    //
+    // See longer explanation in CSSAnimation::CancelFromStyle.
+    mAnimationIndex = sNextAnimationIndex++;
+    mNeedsNewAnimationIndexWhenRun = true;
+
+    Animation::Cancel(aPostRestyle);
+
+    // It is important we do this *after* calling Cancel().
+    // This is because Cancel() will end up posting a restyle and
+    // that restyle should target the *transitions* level of the cascade.
+    // However, once we clear the owning element, CascadeLevel() will begin
+    // returning CascadeLevel::Animations.
+    mOwningElement = OwningElementRef();
+  }
+
+  void SetEffectFromStyle(AnimationEffect* aEffect);
+
+  void Tick() override;
+
+  nsCSSPropertyID TransitionProperty() const;
+  AnimationValue ToValue() const;
+
+  bool HasLowerCompositeOrderThan(const CSSTransition& aOther) const;
+  EffectCompositor::CascadeLevel CascadeLevel() const override {
+    return IsTiedToMarkup() ? EffectCompositor::CascadeLevel::Transitions
+                            : EffectCompositor::CascadeLevel::Animations;
+  }
+
+  void SetCreationSequence(uint64_t aIndex) {
+    MOZ_ASSERT(IsTiedToMarkup());
+    mAnimationIndex = aIndex;
+  }
+
+  // Sets the owning element which is used for determining the composite
+  // oder of CSSTransition objects generated from CSS markup.
+  //
+  // @see mOwningElement
+  void SetOwningElement(const OwningElementRef& aElement) {
+    mOwningElement = aElement;
+  }
+  // True for transitions that are generated from CSS markup and continue to
+  // reflect changes to that markup.
+  bool IsTiedToMarkup() const { return mOwningElement.IsSet(); }
+
+  // Return the animation current time based on a given TimeStamp, a given
+  // start time and a given playbackRate on a given timeline.  This is useful
+  // when we estimate the current animated value running on the compositor
+  // because the animation on the compositor may be running ahead while
+  // main-thread is busy.
+  static Nullable<TimeDuration> GetCurrentTimeAt(
+      const AnimationTimeline& aTimeline, const TimeStamp& aBaseTime,
+      const TimeDuration& aStartTime, double aPlaybackRate);
+
+  void MaybeQueueCancelEvent(const StickyTimeDuration& aActiveTime) override {
+    QueueEvents(aActiveTime);
+  }
+
+  // Compute the portion of the *value* space that we should be through
+  // at the current time.  (The input to the transition timing function
+  // has time units, the output has value units.)
+  double CurrentValuePortion() const;
+
+  const AnimationValue& StartForReversingTest() const {
+    return mStartForReversingTest;
+  }
+  double ReversePortion() const { return mReversePortion; }
+
+  void SetReverseParameters(AnimationValue&& aStartForReversingTest,
+                            double aReversePortion) {
+    mStartForReversingTest = std::move(aStartForReversingTest);
+    mReversePortion = aReversePortion;
+  }
+
+  struct ReplacedTransitionProperties {
+    TimeDuration mStartTime;
+    double mPlaybackRate;
+    TimingParams mTiming;
+    Maybe<ComputedTimingFunction> mTimingFunction;
+    AnimationValue mFromValue, mToValue;
+  };
+  void SetReplacedTransition(
+      ReplacedTransitionProperties&& aReplacedTransition) {
+    mReplacedTransition.emplace(std::move(aReplacedTransition));
+  }
+
+  // For a new transition interrupting an existing transition on the
+  // compositor, update the start value to match the value of the replaced
+  // transitions at the current time.
+  void UpdateStartValueFromReplacedTransition();
+
+ protected:
+  virtual ~CSSTransition() {
+    MOZ_ASSERT(!mOwningElement.IsSet(),
+               "Owning element should be cleared "
+               "before a CSS transition is destroyed");
+  }
+
+  // Animation overrides
+  void UpdateTiming(SeekFlag aSeekFlag,
+                    SyncNotifyFlag aSyncNotifyFlag) override;
+
+  void QueueEvents(const StickyTimeDuration& activeTime = StickyTimeDuration());
+
+  enum class TransitionPhase;
+
+  // The (pseudo-)element whose computed transition-property refers to this
+  // transition (if any).
+  //
+  // This is used for determining the relative composite order of transitions
+  // generated from CSS markup.
+  //
+  // Typically this will be the same as the target element of the keyframe
+  // effect associated with this transition. However, it can differ in the
+  // following circumstances:
+  //
+  // a) If script removes or replaces the effect of this transition,
+  // b) If this transition is cancelled (e.g. by updating the
+  //    transition-property or removing the owning element from the document),
+  // c) If this object is generated from script using the CSSTransition
+  //    constructor.
+  //
+  // For (b) and (c) the owning element will return !IsSet().
+  OwningElementRef mOwningElement;
+
+  // The 'transition phase' used to determine which transition events need
+  // to be queued on this tick.
+  // See: https://drafts.csswg.org/css-transitions-2/#transition-phase
+  enum class TransitionPhase {
+    Idle = static_cast<int>(ComputedTiming::AnimationPhase::Idle),
+    Before = static_cast<int>(ComputedTiming::AnimationPhase::Before),
+    Active = static_cast<int>(ComputedTiming::AnimationPhase::Active),
+    After = static_cast<int>(ComputedTiming::AnimationPhase::After),
+    Pending
+  };
+  TransitionPhase mPreviousTransitionPhase;
+
+  // When true, indicates that when this transition next leaves the idle state,
+  // its animation index should be updated.
+  bool mNeedsNewAnimationIndexWhenRun;
+
+  // Store the transition property and to-value here since we need that
+  // information in order to determine if there is an existing transition
+  // for a given style change. We can't store that information on the
+  // effect however since it can be replaced using the Web Animations API.
+  nsCSSPropertyID mTransitionProperty;
+  AnimationValue mTransitionToValue;
+
+  // This is the start value to be used for a check for whether a
+  // transition is being reversed.  Normally the same as
+  // mEffect->mProperties[0].mSegments[0].mFromValue, except when this
+  // transition started as the reversal of another in-progress transition
+  // or when the effect has been mutated using the Web Animations API.
+  //
+  // Needed so we can handle two reverses in a row.
+  AnimationValue mStartForReversingTest;
+
+  // Likewise, the portion (in value space) of the "full" reversed
+  // transition that we're actually covering.  For example, if a :hover
+  // effect has a transition that moves the element 10px to the right
+  // (by changing 'left' from 0px to 10px), and the mouse moves in to
+  // the element (starting the transition) but then moves out after the
+  // transition has advanced 4px, the second transition (from 10px/4px
+  // to 0px) will have mReversePortion of 0.4.  (If the mouse then moves
+  // in again when the transition is back to 2px, the mReversePortion
+  // for the third transition (from 0px/2px to 10px) will be 0.8.
+  double mReversePortion = 1.0;
+
+  Maybe<ReplacedTransitionProperties> mReplacedTransition;
+};
+
+}  // namespace dom
+
+template <>
+struct AnimationTypeTraits<dom::CSSTransition> {
+  static nsAtom* ElementPropertyAtom() {
+    return nsGkAtoms::transitionsProperty;
+  }
+  static nsAtom* BeforePropertyAtom() {
+    return nsGkAtoms::transitionsOfBeforeProperty;
+  }
+  static nsAtom* AfterPropertyAtom() {
+    return nsGkAtoms::transitionsOfAfterProperty;
+  }
+  static nsAtom* MarkerPropertyAtom() {
+    return nsGkAtoms::transitionsOfMarkerProperty;
+  }
+};
+
+}  // namespace mozilla
+
+#endif  // mozilla_dom_CSSTransition_h

dom/animation/DocumentTimeline.cpp

@@ -4,6 +4,7 @@
 
 #include "DocumentTimeline.h"
 #include "mozilla/ScopeExit.h"
+#include "mozilla/dom/DocumentInlines.h"
 #include "mozilla/dom/DocumentTimelineBinding.h"
 #include "AnimationUtils.h"
 #include "nsContentUtils.h"
@@ -58,8 +59,7 @@ already_AddRefed<DocumentTimeline> DocumentTimeline::Constructor(
 
   if (originTime == TimeDuration::Forever() ||
       originTime == -TimeDuration::Forever()) {
-    aRv.ThrowTypeError<dom::MSG_TIME_VALUE_OUT_OF_RANGE>(
-        NS_LITERAL_STRING("Origin time"));
+    aRv.ThrowTypeError<dom::MSG_TIME_VALUE_OUT_OF_RANGE>("Origin time");
     return nullptr;
   }
   RefPtr<DocumentTimeline> timeline = new DocumentTimeline(doc, originTime);

dom/animation/EffectCompositor.cpp

@@ -269,6 +269,12 @@ void EffectCompositor::PostRestyleForAnimation(dom::Element* aElement,
     return;
   }
 
+  // FIXME: Bug 1615083 KeyframeEffect::SetTarget() and
+  // KeyframeEffect::SetPseudoElement() may set a non-existing pseudo element,
+  // and we still have to update its style, based on the wpt. However, we don't
+  // have the generated element here, so we failed the wpt.
+  //
+  // See wpt for more info: web-animations/interfaces/KeyframeEffect/target.html
   dom::Element* element = GetElementToRestyle(aElement, aPseudoType);
   if (!element) {
     return;
@@ -389,19 +395,31 @@ static void ComposeSortedEffects(
     const nsTArray<KeyframeEffect*>& aSortedEffects,
     const EffectSet* aEffectSet, EffectCompositor::CascadeLevel aCascadeLevel,
     RawServoAnimationValueMap* aAnimationValues) {
-  // If multiple animations affect the same property, animations with higher
-  // composite order (priority) override or add to animations with lower
-  // priority.
+  const bool isTransition =
+      aCascadeLevel == EffectCompositor::CascadeLevel::Transitions;
   nsCSSPropertyIDSet propertiesToSkip;
+  // Transitions should be overridden by running animations of the same
+  // property per https://drafts.csswg.org/css-transitions/#application:
+  //
+  // > Implementations must add this value to the cascade if and only if that
+  // > property is not currently undergoing a CSS Animation on the same element.
+  //
+  // FIXME(emilio, bug 1606176): This should assert that
+  // aEffectSet->PropertiesForAnimationsLevel() is up-to-date, and it may not
+  // follow the spec in those cases. There are various places where we get style
+  // without flushing that would trigger the below assertion.
+  //
+  // MOZ_ASSERT_IF(aEffectSet, !aEffectSet->CascadeNeedsUpdate());
   if (aEffectSet) {
     propertiesToSkip =
-        aCascadeLevel == EffectCompositor::CascadeLevel::Animations
-            ? aEffectSet->PropertiesForAnimationsLevel().Inverse()
-            : aEffectSet->PropertiesForAnimationsLevel();
+        isTransition ? aEffectSet->PropertiesForAnimationsLevel()
+                     : aEffectSet->PropertiesForAnimationsLevel().Inverse();
   }
 
   for (KeyframeEffect* effect : aSortedEffects) {
-    effect->GetAnimation()->ComposeStyle(*aAnimationValues, propertiesToSkip);
+    auto* animation = effect->GetAnimation();
+    MOZ_ASSERT(!isTransition || animation->CascadeLevel() == aCascadeLevel);
+    animation->ComposeStyle(*aAnimationValues, propertiesToSkip);
   }
 }
 
@@ -421,11 +439,27 @@ bool EffectCompositor::GetServoAnimationRule(
     return false;
   }
 
+  const bool isTransition = aCascadeLevel == CascadeLevel::Transitions;
+
   // Get a list of effects sorted by composite order.
   nsTArray<KeyframeEffect*> sortedEffectList(effectSet->Count());
   for (KeyframeEffect* effect : *effectSet) {
+    if (isTransition &&
+        effect->GetAnimation()->CascadeLevel() != aCascadeLevel) {
+      // We may need to use transition rules for the animations level for the
+      // case of missing keyframes in animations, but we don't ever need to look
+      // at non-transition levels to build a transition rule. When the effect
+      // set information is out of date (see above), this avoids creating bogus
+      // transition rules, see bug 1605610.
+      continue;
+    }
     sortedEffectList.AppendElement(effect);
   }
+
+  if (sortedEffectList.IsEmpty()) {
+    return false;
+  }
+
   sortedEffectList.Sort(EffectCompositeOrderComparator());
 
   ComposeSortedEffects(sortedEffectList, effectSet, aCascadeLevel,
@@ -444,14 +478,14 @@ bool EffectCompositor::ComposeServoAnimationRuleForEffect(
   MOZ_ASSERT(mPresContext && mPresContext->IsDynamic(),
              "Should not be in print preview");
 
-  Maybe<NonOwningAnimationTarget> target = aEffect.GetTarget();
+  NonOwningAnimationTarget target = aEffect.GetAnimationTarget();
   if (!target) {
     return false;
   }
 
   // Don't try to compose animations for elements in documents without a pres
   // shell (e.g. XMLHttpRequest documents).
-  if (!nsContentUtils::GetPresShellForContent(target->mElement)) {
+  if (!nsContentUtils::GetPresShellForContent(target.mElement)) {
     return false;
   }
 
@@ -459,11 +493,10 @@ bool EffectCompositor::ComposeServoAnimationRuleForEffect(
   // where the cascade results are updated in the pre-traversal as needed.
   // This function, however, is only called when committing styles so we
   // need to ensure the cascade results are up-to-date manually.
-  EffectCompositor::MaybeUpdateCascadeResults(target->mElement,
-                                              target->mPseudoType);
+  MaybeUpdateCascadeResults(target.mElement, target.mPseudoType);
 
   EffectSet* effectSet =
-      EffectSet::GetEffectSet(target->mElement, target->mPseudoType);
+      EffectSet::GetEffectSet(target.mElement, target.mPseudoType);
 
   // Get a list of effects sorted by composite order up to and including
   // |aEffect|, even if it is not in the EffectSet.
@@ -483,9 +516,9 @@ bool EffectCompositor::ComposeServoAnimationRuleForEffect(
   ComposeSortedEffects(sortedEffectList, effectSet, aCascadeLevel,
                        aAnimationValues);
 
-  MOZ_ASSERT(effectSet ==
-                 EffectSet::GetEffectSet(target->mElement, target->mPseudoType),
-             "EffectSet should not change while composing style");
+  MOZ_ASSERT(
+      effectSet == EffectSet::GetEffectSet(target.mElement, target.mPseudoType),
+      "EffectSet should not change while composing style");
 
   return true;
 }

dom/animation/EffectSet.cpp

@@ -5,6 +5,7 @@
 #include "EffectSet.h"
 #include "mozilla/dom/Element.h"  // For Element
 #include "mozilla/RestyleManager.h"
+#include "mozilla/LayerAnimationInfo.h"
 #include "nsCSSPseudoElements.h"         // For PseudoStyleType
 #include "nsCycleCollectionNoteChild.h"  // For CycleCollectionNoteChild
 #include "nsPresContext.h"
@@ -135,7 +136,7 @@ void EffectSet::DestroyEffectSet(dom::Element* aElement,
              "Should not destroy an effect set while it is being enumerated");
   effectSet = nullptr;
 
-  aElement->DeleteProperty(propName);
+  aElement->RemoveProperty(propName);
 }
 
 void EffectSet::UpdateAnimationGeneration(nsPresContext* aPresContext) {

dom/animation/Keyframe.h

@@ -61,17 +61,10 @@ struct PropertyValuePair {
 struct Keyframe {
   Keyframe() = default;
   Keyframe(const Keyframe& aOther) = default;
-  Keyframe(Keyframe&& aOther) { *this = std::move(aOther); }
+  Keyframe(Keyframe&& aOther) = default;
 
   Keyframe& operator=(const Keyframe& aOther) = default;
-  Keyframe& operator=(Keyframe&& aOther) {
-    mOffset = aOther.mOffset;
-    mComputedOffset = aOther.mComputedOffset;
-    mTimingFunction = std::move(aOther.mTimingFunction);
-    mComposite = std::move(aOther.mComposite);
-    mPropertyValues = std::move(aOther.mPropertyValues);
-    return *this;
-  }
+  Keyframe& operator=(Keyframe&& aOther) = default;
 
   Maybe<double> mOffset;
   static constexpr double kComputedOffsetNotSet = -1.0;

dom/animation/KeyframeEffect.cpp

@@ -8,7 +8,6 @@
 #include "mozilla/dom/Animation.h"
 #include "mozilla/dom/KeyframeAnimationOptionsBinding.h"
 // For UnrestrictedDoubleOrKeyframeAnimationOptions;
-#include "mozilla/dom/CSSPseudoElement.h"
 #include "mozilla/dom/KeyframeEffectBinding.h"
 #include "mozilla/dom/MutationObservers.h"
 #include "mozilla/AnimationUtils.h"
@@ -34,13 +33,14 @@
 #include "nsCSSPseudoElements.h"    // For PseudoStyleType
 #include "nsDOMMutationObserver.h"  // For nsAutoAnimationMutationBatch
 #include "nsIFrame.h"
+#include "nsIFrameInlines.h"
 #include "nsPresContextInlines.h"
 #include "nsRefreshDriver.h"
 
 namespace mozilla {
 
 void AnimationProperty::SetPerformanceWarning(
-    const AnimationPerformanceWarning& aWarning, const Element* aElement) {
+    const AnimationPerformanceWarning& aWarning, const dom::Element* aElement) {
   if (mPerformanceWarning && *mPerformanceWarning == aWarning) {
     return;
   }
@@ -71,7 +71,8 @@ bool PropertyValuePair::operator==(const PropertyValuePair& aOther) const {
 
 namespace dom {
 
-NS_IMPL_CYCLE_COLLECTION_INHERITED(KeyframeEffect, AnimationEffect, mTarget)
+NS_IMPL_CYCLE_COLLECTION_INHERITED(KeyframeEffect, AnimationEffect,
+                                   mTarget.mElement)
 
 NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN_INHERITED(KeyframeEffect, AnimationEffect)
 NS_IMPL_CYCLE_COLLECTION_TRACE_END
@@ -83,11 +84,11 @@ NS_IMPL_ADDREF_INHERITED(KeyframeEffect, AnimationEffect)
 NS_IMPL_RELEASE_INHERITED(KeyframeEffect, AnimationEffect)
 
 KeyframeEffect::KeyframeEffect(Document* aDocument,
-                               const Maybe<OwningAnimationTarget>& aTarget,
+                               OwningAnimationTarget&& aTarget,
                                TimingParams&& aTiming,
                                const KeyframeEffectParams& aOptions)
     : AnimationEffect(aDocument, std::move(aTiming)),
-      mTarget(aTarget),
+      mTarget(std::move(aTarget)),
       mEffectOptions(aOptions),
       mCumulativeChangeHint(nsChangeHint(0)) {}
 
@@ -140,7 +141,7 @@ void KeyframeEffect::SetComposite(const CompositeOperation& aComposite) {
 void KeyframeEffect::NotifySpecifiedTimingUpdated() {
   // Use the same document for a pseudo element and its parent element.
   // Use nullptr if we don't have mTarget, so disable the mutation batch.
-  nsAutoAnimationMutationBatch mb(mTarget ? mTarget->mElement->OwnerDoc()
+  nsAutoAnimationMutationBatch mb(mTarget ? mTarget.mElement->OwnerDoc()
                                           : nullptr);
 
   if (mAnimation) {
@@ -221,7 +222,7 @@ void KeyframeEffect::SetKeyframes(JSContext* aContext,
                                   JS::Handle<JSObject*> aKeyframes,
                                   ErrorResult& aRv) {
   nsTArray<Keyframe> keyframes = KeyframeUtils::GetKeyframesFromObject(
-      aContext, mDocument, aKeyframes, "KeyframeEffect.setKeyframes: ", aRv);
+      aContext, mDocument, aKeyframes, "KeyframeEffect.setKeyframes", aRv);
   if (aRv.Failed()) {
     return;
   }
@@ -250,6 +251,36 @@ void KeyframeEffect::SetKeyframes(nsTArray<Keyframe>&& aKeyframes,
   }
 }
 
+void KeyframeEffect::ReplaceTransitionStartValue(AnimationValue&& aStartValue) {
+  if (!aStartValue.mServo) {
+    return;
+  }
+
+  // A typical transition should have a single property and a single segment.
+  //
+  // (And for atypical transitions, that is, those updated by script, we don't
+  // apply the replacing behavior.)
+  if (mProperties.Length() != 1 || mProperties[0].mSegments.Length() != 1) {
+    return;
+  }
+
+  // Likewise, check that the keyframes are of the expected shape.
+  if (mKeyframes.Length() != 2 || mKeyframes[0].mPropertyValues.Length() != 1) {
+    return;
+  }
+
+  // Check that the value we are about to substitute in is actually for the
+  // same property.
+  if (Servo_AnimationValue_GetPropertyId(aStartValue.mServo) !=
+      mProperties[0].mProperty) {
+    return;
+  }
+
+  mKeyframes[0].mPropertyValues[0].mServoDeclarationBlock =
+      Servo_AnimationValue_Uncompute(aStartValue.mServo).Consume();
+  mProperties[0].mSegments[0].mFromValue = std::move(aStartValue);
+}
+
 static bool IsEffectiveProperty(const EffectSet& aEffects,
                                 nsCSSPropertyID aProperty) {
   return !aEffects.PropertiesWithImportantRules().HasProperty(aProperty) ||
@@ -258,8 +289,9 @@ static bool IsEffectiveProperty(const EffectSet& aEffects,
 
 const AnimationProperty* KeyframeEffect::GetEffectiveAnimationOfProperty(
     nsCSSPropertyID aProperty, const EffectSet& aEffects) const {
-  MOZ_ASSERT(&aEffects ==
-             EffectSet::GetEffectSet(mTarget->mElement, mTarget->mPseudoType));
+  MOZ_ASSERT(mTarget &&
+             &aEffects == EffectSet::GetEffectSet(mTarget.mElement,
+                                                  mTarget.mPseudoType));
 
   for (const AnimationProperty& property : mProperties) {
     if (aProperty != property.mProperty) {
@@ -291,7 +323,7 @@ bool KeyframeEffect::HasEffectiveAnimationOfPropertySet(
 nsCSSPropertyIDSet KeyframeEffect::GetPropertiesForCompositor(
     EffectSet& aEffects, const nsIFrame* aFrame) const {
   MOZ_ASSERT(&aEffects ==
-             EffectSet::GetEffectSet(mTarget->mElement, mTarget->mPseudoType));
+             EffectSet::GetEffectSet(mTarget.mElement, mTarget.mPseudoType));
 
   nsCSSPropertyIDSet properties;
 
@@ -372,6 +404,16 @@ bool SpecifiedKeyframeArraysAreEqual(const nsTArray<Keyframe>& aA,
 }
 #endif
 
+static bool HasCurrentColor(
+    const nsTArray<AnimationPropertySegment>& aSegments) {
+  for (const AnimationPropertySegment& segment : aSegments) {
+    if ((!segment.mFromValue.IsNull() && segment.mFromValue.IsCurrentColor()) ||
+        (!segment.mToValue.IsNull() && segment.mToValue.IsCurrentColor())) {
+      return true;
+    }
+  }
+  return false;
+}
 void KeyframeEffect::UpdateProperties(const ComputedStyle* aStyle) {
   MOZ_ASSERT(aStyle);
 
@@ -391,7 +433,7 @@ void KeyframeEffect::UpdateProperties(const ComputedStyle* aStyle) {
     }
     // Check if we need to update the cumulative change hint because we now have
     // style data.
-    if (mNeedsStyleData && mTarget && mTarget->mElement->HasServoData()) {
+    if (mNeedsStyleData && mTarget && mTarget.mElement->HasServoData()) {
       CalculateCumulativeChangeHint(aStyle);
     }
     return;
@@ -409,9 +451,19 @@ void KeyframeEffect::UpdateProperties(const ComputedStyle* aStyle) {
   mProperties = std::move(properties);
   UpdateEffectSet();
 
+  mHasCurrentColor = false;
+
   for (AnimationProperty& property : mProperties) {
     property.mIsRunningOnCompositor =
         runningOnCompositorProperties.HasProperty(property.mProperty);
+
+    if (property.mProperty == eCSSProperty_background_color &&
+        !mHasCurrentColor) {
+      if (HasCurrentColor(property.mSegments)) {
+        mHasCurrentColor = true;
+        break;
+      }
+    }
   }
 
   CalculateCumulativeChangeHint(aStyle);
@@ -444,7 +496,7 @@ void KeyframeEffect::EnsureBaseStyles(
   mBaseValues.Clear();
 
   nsPresContext* presContext =
-      nsContentUtils::GetContextForContent(mTarget->mElement);
+      nsContentUtils::GetContextForContent(mTarget.mElement);
   // If |aProperties| is empty we're not going to dereference |presContext| so
   // we don't care if it is nullptr.
   //
@@ -493,8 +545,10 @@ void KeyframeEffect::EnsureBaseStyle(
   }
 
   if (!aBaseComputedStyle) {
+    MOZ_ASSERT(mTarget, "Should have a valid target");
+
     Element* animatingElement = EffectCompositor::GetElementToRestyle(
-        mTarget->mElement, mTarget->mPseudoType);
+        mTarget.mElement, mTarget.mPseudoType);
     if (!animatingElement) {
       return;
     }
@@ -505,7 +559,7 @@ void KeyframeEffect::EnsureBaseStyle(
       Servo_ComputedValues_ExtractAnimationValue(aBaseComputedStyle,
                                                  aProperty.mProperty)
           .Consume();
-  mBaseValues.Put(aProperty.mProperty, baseValue);
+  mBaseValues.Put(aProperty.mProperty, std::move(baseValue));
 }
 
 void KeyframeEffect::WillComposeStyle() {
@@ -578,9 +632,9 @@ void KeyframeEffect::ComposeStyle(RawServoAnimationValueMap& aComposeResult,
   // out of view.
   if (HasPropertiesThatMightAffectOverflow()) {
     nsPresContext* presContext =
-        nsContentUtils::GetContextForContent(mTarget->mElement);
+        nsContentUtils::GetContextForContent(mTarget.mElement);
     EffectSet* effectSet =
-        EffectSet::GetEffectSet(mTarget->mElement, mTarget->mPseudoType);
+        EffectSet::GetEffectSet(mTarget.mElement, mTarget.mPseudoType);
     if (presContext && effectSet) {
       TimeStamp now = presContext->RefreshDriver()->MostRecentRefresh();
       effectSet->UpdateLastOverflowAnimationSyncTime(now);
@@ -646,6 +700,12 @@ void KeyframeEffect::ResetIsRunningOnCompositor() {
   }
 }
 
+static bool IsSupportedPseudoForWebAnimation(PseudoStyleType aType) {
+  // FIXME: Bug 1615469: Support first-line and first-letter for Web Animation.
+  return aType == PseudoStyleType::before || aType == PseudoStyleType::after ||
+         aType == PseudoStyleType::marker;
+}
+
 static const KeyframeEffectOptions& KeyframeEffectOptionsFromUnion(
     const UnrestrictedDoubleOrKeyframeEffectOptions& aOptions) {
   MOZ_ASSERT(aOptions.IsKeyframeEffectOptions());
@@ -660,50 +720,52 @@ static const KeyframeEffectOptions& KeyframeEffectOptionsFromUnion(
 
 template <class OptionsType>
 static KeyframeEffectParams KeyframeEffectParamsFromUnion(
-    const OptionsType& aOptions, CallerType aCallerType) {
+    const OptionsType& aOptions, CallerType aCallerType, ErrorResult& aRv) {
   KeyframeEffectParams result;
-  if (aOptions.IsUnrestrictedDouble() ||
-      // Ignore iterationComposite and composite if the corresponding pref is
-      // not set. The default value 'Replace' will be used instead.
-      !StaticPrefs::dom_animations_api_compositing_enabled()) {
+  if (aOptions.IsUnrestrictedDouble()) {
     return result;
   }
 
   const KeyframeEffectOptions& options =
       KeyframeEffectOptionsFromUnion(aOptions);
+
+  // If dom.animations-api.compositing.enabled is turned off,
+  // iterationComposite and composite are the default value 'replace' in the
+  // dictionary.
   result.mIterationComposite = options.mIterationComposite;
   result.mComposite = options.mComposite;
-  return result;
-}
 
-/* static */
-Maybe<OwningAnimationTarget> KeyframeEffect::ConvertTarget(
-    const Nullable<ElementOrCSSPseudoElement>& aTarget) {
-  // Return value optimization.
-  Maybe<OwningAnimationTarget> result;
-
-  if (aTarget.IsNull()) {
+  result.mPseudoType = PseudoStyleType::NotPseudo;
+  if (DOMStringIsNull(options.mPseudoElement)) {
     return result;
   }
 
-  const ElementOrCSSPseudoElement& target = aTarget.Value();
-  MOZ_ASSERT(target.IsElement() || target.IsCSSPseudoElement(),
-             "Uninitialized target");
-
-  if (target.IsElement()) {
-    result.emplace(&target.GetAsElement());
-  } else {
-    RefPtr<Element> elem = target.GetAsCSSPseudoElement().Element();
-    result.emplace(elem, target.GetAsCSSPseudoElement().GetType());
+  RefPtr<nsAtom> pseudoAtom =
+      nsCSSPseudoElements::GetPseudoAtom(options.mPseudoElement);
+  if (!pseudoAtom) {
+    // Per the spec, we throw SyntaxError for syntactically invalid pseudos.
+    aRv.ThrowSyntaxError(
+        nsPrintfCString("'%s' is a syntactically invalid pseudo-element.",
+                        NS_ConvertUTF16toUTF8(options.mPseudoElement).get()));
+    return result;
   }
+
+  result.mPseudoType = nsCSSPseudoElements::GetPseudoType(
+      pseudoAtom, CSSEnabledState::ForAllContent);
+  if (!IsSupportedPseudoForWebAnimation(result.mPseudoType)) {
+    // Per the spec, we throw SyntaxError for unsupported pseudos.
+    aRv.ThrowSyntaxError(
+        nsPrintfCString("'%s' is an unsupported pseudo-element.",
+                        NS_ConvertUTF16toUTF8(options.mPseudoElement).get()));
+  }
+
   return result;
 }
 
 template <class OptionsType>
 /* static */
 already_AddRefed<KeyframeEffect> KeyframeEffect::ConstructKeyframeEffect(
-    const GlobalObject& aGlobal,
-    const Nullable<ElementOrCSSPseudoElement>& aTarget,
+    const GlobalObject& aGlobal, Element* aTarget,
     JS::Handle<JSObject*> aKeyframes, const OptionsType& aOptions,
     ErrorResult& aRv) {
   // We should get the document from `aGlobal` instead of the current Realm
@@ -721,18 +783,22 @@ already_AddRefed<KeyframeEffect> KeyframeEffect::ConstructKeyframeEffect(
     return nullptr;
   }
 
+  KeyframeEffectParams effectOptions =
+      KeyframeEffectParamsFromUnion(aOptions, aGlobal.CallerType(), aRv);
+  // An invalid Pseudo-element aborts all further steps.
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+
   TimingParams timingParams =
       TimingParams::FromOptionsUnion(aOptions, doc, aRv);
   if (aRv.Failed()) {
     return nullptr;
   }
 
-  KeyframeEffectParams effectOptions =
-      KeyframeEffectParamsFromUnion(aOptions, aGlobal.CallerType());
-
-  Maybe<OwningAnimationTarget> target = ConvertTarget(aTarget);
-  RefPtr<KeyframeEffect> effect =
-      new KeyframeEffect(doc, target, std::move(timingParams), effectOptions);
+  RefPtr<KeyframeEffect> effect = new KeyframeEffect(
+      doc, OwningAnimationTarget(aTarget, effectOptions.mPseudoType),
+      std::move(timingParams), effectOptions);
 
   effect->SetKeyframes(aGlobal.Context(), aKeyframes, aRv);
   if (aRv.Failed()) {
@@ -747,7 +813,8 @@ nsTArray<AnimationProperty> KeyframeEffect::BuildProperties(
   MOZ_ASSERT(aStyle);
 
   nsTArray<AnimationProperty> result;
-  // If mTarget is null, return an empty property array.
+  // If mTarget is false (i.e. mTarget.mElement is null), return an empty
+  // property array.
   if (!mTarget) {
     return result;
   }
@@ -761,7 +828,7 @@ nsTArray<AnimationProperty> KeyframeEffect::BuildProperties(
   auto keyframesCopy(mKeyframes);
 
   result = KeyframeUtils::GetAnimationPropertiesFromKeyframes(
-      keyframesCopy, mTarget->mElement, aStyle, mEffectOptions.mComposite);
+      keyframesCopy, mTarget.mElement, aStyle, mEffectOptions.mComposite);
 
 #ifdef DEBUG
   MOZ_ASSERT(SpecifiedKeyframeArraysAreEqual(mKeyframes, keyframesCopy),
@@ -782,6 +849,50 @@ static void EnumerateContinuationsOrIBSplitSiblings(nsIFrame* aFrame,
   }
 }
 
+void KeyframeEffect::UpdateTarget(Element* aElement,
+                                  PseudoStyleType aPseudoType) {
+  OwningAnimationTarget newTarget(aElement, aPseudoType);
+
+  if (mTarget == newTarget) {
+    // Assign the same target, skip it.
+    return;
+  }
+
+  if (mTarget) {
+    UnregisterTarget();
+    ResetIsRunningOnCompositor();
+
+    RequestRestyle(EffectCompositor::RestyleType::Layer);
+
+    nsAutoAnimationMutationBatch mb(mTarget.mElement->OwnerDoc());
+    if (mAnimation) {
+      MutationObservers::NotifyAnimationRemoved(mAnimation);
+    }
+  }
+
+  mTarget = newTarget;
+
+  if (mTarget) {
+    UpdateTargetRegistration();
+    RefPtr<ComputedStyle> computedStyle = GetTargetComputedStyle(Flush::None);
+    if (computedStyle) {
+      UpdateProperties(computedStyle);
+    }
+
+    RequestRestyle(EffectCompositor::RestyleType::Layer);
+
+    nsAutoAnimationMutationBatch mb(mTarget.mElement->OwnerDoc());
+    if (mAnimation) {
+      MutationObservers::NotifyAnimationAdded(mAnimation);
+      mAnimation->ReschedulePendingTasks();
+    }
+  }
+
+  if (mAnimation) {
+    mAnimation->NotifyEffectTargetUpdated();
+  }
+}
+
 void KeyframeEffect::UpdateTargetRegistration() {
   if (!mTarget) {
     return;
@@ -799,8 +910,8 @@ void KeyframeEffect::UpdateTargetRegistration() {
              "Out of date Animation::IsRelevant value");
 
   if (isRelevant && !mInEffectSet) {
-    EffectSet* effectSet = EffectSet::GetOrCreateEffectSet(
-        mTarget->mElement, mTarget->mPseudoType);
+    EffectSet* effectSet =
+        EffectSet::GetOrCreateEffectSet(mTarget.mElement, mTarget.mPseudoType);
     effectSet->AddEffect(*this);
     mInEffectSet = true;
     UpdateEffectSet(effectSet);
@@ -818,7 +929,7 @@ void KeyframeEffect::UnregisterTarget() {
   }
 
   EffectSet* effectSet =
-      EffectSet::GetEffectSet(mTarget->mElement, mTarget->mPseudoType);
+      EffectSet::GetEffectSet(mTarget.mElement, mTarget.mPseudoType);
   MOZ_ASSERT(effectSet,
              "If mInEffectSet is true, there must be an EffectSet"
              " on the target element");
@@ -827,7 +938,7 @@ void KeyframeEffect::UnregisterTarget() {
     effectSet->RemoveEffect(*this);
 
     if (effectSet->IsEmpty()) {
-      EffectSet::DestroyEffectSet(mTarget->mElement, mTarget->mPseudoType);
+      EffectSet::DestroyEffectSet(mTarget.mElement, mTarget.mPseudoType);
     }
   }
   nsIFrame* frame = GetPrimaryFrame();
@@ -841,10 +952,10 @@ void KeyframeEffect::RequestRestyle(
     return;
   }
   nsPresContext* presContext =
-      nsContentUtils::GetContextForContent(mTarget->mElement);
+      nsContentUtils::GetContextForContent(mTarget.mElement);
   if (presContext && mAnimation) {
     presContext->EffectCompositor()->RequestRestyle(
-        mTarget->mElement, mTarget->mPseudoType, aRestyleType,
+        mTarget.mElement, mTarget.mPseudoType, aRestyleType,
         mAnimation->CascadeLevel());
   }
 }
@@ -858,17 +969,15 @@ already_AddRefed<ComputedStyle> KeyframeEffect::GetTargetComputedStyle(
   MOZ_ASSERT(mTarget,
              "Should only have a document when we have a target element");
 
-  nsAtom* pseudo =
-      PseudoStyle::IsPseudoElement(mTarget->mPseudoType)
-          ? nsCSSPseudoElements::GetPseudoAtom(mTarget->mPseudoType)
-          : nullptr;
+  nsAtom* pseudo = PseudoStyle::IsPseudoElement(mTarget.mPseudoType)
+                       ? nsCSSPseudoElements::GetPseudoAtom(mTarget.mPseudoType)
+                       : nullptr;
 
-  OwningAnimationTarget kungfuDeathGrip(mTarget->mElement,
-                                        mTarget->mPseudoType);
+  OwningAnimationTarget kungfuDeathGrip(mTarget.mElement, mTarget.mPseudoType);
 
   return aFlushType == Flush::Style
-             ? nsComputedDOMStyle::GetComputedStyle(mTarget->mElement, pseudo)
-             : nsComputedDOMStyle::GetComputedStyleNoFlush(mTarget->mElement,
+             ? nsComputedDOMStyle::GetComputedStyle(mTarget.mElement, pseudo)
+             : nsComputedDOMStyle::GetComputedStyleNoFlush(mTarget.mElement,
                                                            pseudo);
 }
 
@@ -891,8 +1000,7 @@ void DumpAnimationProperties(
 
 /* static */
 already_AddRefed<KeyframeEffect> KeyframeEffect::Constructor(
-    const GlobalObject& aGlobal,
-    const Nullable<ElementOrCSSPseudoElement>& aTarget,
+    const GlobalObject& aGlobal, Element* aTarget,
     JS::Handle<JSObject*> aKeyframes,
     const UnrestrictedDoubleOrKeyframeEffectOptions& aOptions,
     ErrorResult& aRv) {
@@ -901,8 +1009,7 @@ already_AddRefed<KeyframeEffect> KeyframeEffect::Constructor(
 
 /* static */
 already_AddRefed<KeyframeEffect> KeyframeEffect::Constructor(
-    const GlobalObject& aGlobal,
-    const Nullable<ElementOrCSSPseudoElement>& aTarget,
+    const GlobalObject& aGlobal, Element* aTarget,
     JS::Handle<JSObject*> aKeyframes,
     const UnrestrictedDoubleOrKeyframeAnimationOptions& aOptions,
     ErrorResult& aRv) {
@@ -925,8 +1032,8 @@ already_AddRefed<KeyframeEffect> KeyframeEffect::Constructor(
   // Note: we don't need to re-throw exceptions since the value specified on
   //       aSource's timing object can be assumed valid.
   RefPtr<KeyframeEffect> effect = new KeyframeEffect(
-      doc, aSource.mTarget, TimingParams(aSource.SpecifiedTiming()),
-      aSource.mEffectOptions);
+      doc, OwningAnimationTarget(aSource.mTarget),
+      TimingParams(aSource.SpecifiedTiming()), aSource.mEffectOptions);
   // Copy cumulative change hint. mCumulativeChangeHint should be the same as
   // the source one because both of targets are the same.
   effect->mCumulativeChangeHint = aSource.mCumulativeChangeHint;
@@ -936,76 +1043,45 @@ already_AddRefed<KeyframeEffect> KeyframeEffect::Constructor(
   //       computed offsets and rebuild the animation properties.
   effect->mKeyframes = aSource.mKeyframes;
   effect->mProperties = aSource.mProperties;
+  for (auto iter = aSource.mBaseValues.ConstIter(); !iter.Done(); iter.Next()) {
+    // XXX Should this use non-const Iter() and then pass
+    // std::move(iter.Data())? Otherwise aSource might be a const&...
+    effect->mBaseValues.Put(iter.Key(), RefPtr{iter.Data()});
+  }
   return effect.forget();
 }
 
-void KeyframeEffect::GetTarget(
-    Nullable<OwningElementOrCSSPseudoElement>& aRv) const {
-  if (!mTarget) {
-    aRv.SetNull();
+void KeyframeEffect::SetPseudoElement(const nsAString& aPseudoElement,
+                                      ErrorResult& aRv) {
+  PseudoStyleType pseudoType = PseudoStyleType::NotPseudo;
+  if (DOMStringIsNull(aPseudoElement)) {
+    UpdateTarget(mTarget.mElement, pseudoType);
     return;
   }
 
-  switch (mTarget->mPseudoType) {
-    case PseudoStyleType::before:
-    case PseudoStyleType::after:
-    case PseudoStyleType::marker:
-      aRv.SetValue().SetAsCSSPseudoElement() =
-          CSSPseudoElement::GetCSSPseudoElement(mTarget->mElement,
-                                                mTarget->mPseudoType);
-      break;
-
-    case PseudoStyleType::NotPseudo:
-      aRv.SetValue().SetAsElement() = mTarget->mElement;
-      break;
-
-    default:
-      MOZ_ASSERT_UNREACHABLE("Animation of unsupported pseudo-type");
-      aRv.SetNull();
-  }
-}
-
-void KeyframeEffect::SetTarget(
-    const Nullable<ElementOrCSSPseudoElement>& aTarget) {
-  Maybe<OwningAnimationTarget> newTarget = ConvertTarget(aTarget);
-  if (mTarget == newTarget) {
-    // Assign the same target, skip it.
+  // Note: GetPseudoAtom() also returns nullptr for the null string,
+  // so we handle null case before this.
+  RefPtr<nsAtom> pseudoAtom =
+      nsCSSPseudoElements::GetPseudoAtom(aPseudoElement);
+  if (!pseudoAtom) {
+    // Per the spec, we throw SyntaxError for syntactically invalid pseudos.
+    aRv.ThrowSyntaxError(
+        nsPrintfCString("'%s' is a syntactically invalid pseudo-element.",
+                        NS_ConvertUTF16toUTF8(aPseudoElement).get()));
     return;
   }
 
-  if (mTarget) {
-    UnregisterTarget();
-    ResetIsRunningOnCompositor();
-
-    RequestRestyle(EffectCompositor::RestyleType::Layer);
-
-    nsAutoAnimationMutationBatch mb(mTarget->mElement->OwnerDoc());
-    if (mAnimation) {
-      MutationObservers::NotifyAnimationRemoved(mAnimation);
-    }
+  pseudoType = nsCSSPseudoElements::GetPseudoType(
+      pseudoAtom, CSSEnabledState::ForAllContent);
+  if (!IsSupportedPseudoForWebAnimation(pseudoType)) {
+    // Per the spec, we throw SyntaxError for unsupported pseudos.
+    aRv.ThrowSyntaxError(
+        nsPrintfCString("'%s' is an unsupported pseudo-element.",
+                        NS_ConvertUTF16toUTF8(aPseudoElement).get()));
+    return;
   }
 
-  mTarget = newTarget;
-
-  if (mTarget) {
-    UpdateTargetRegistration();
-    RefPtr<ComputedStyle> computedStyle = GetTargetComputedStyle(Flush::None);
-    if (computedStyle) {
-      UpdateProperties(computedStyle);
-    }
-
-    RequestRestyle(EffectCompositor::RestyleType::Layer);
-
-    nsAutoAnimationMutationBatch mb(mTarget->mElement->OwnerDoc());
-    if (mAnimation) {
-      MutationObservers::NotifyAnimationAdded(mAnimation);
-      mAnimation->ReschedulePendingTasks();
-    }
-  }
-
-  if (mAnimation) {
-    mAnimation->NotifyEffectTargetUpdated();
-  }
+  UpdateTarget(mTarget.mElement, pseudoType);
 }
 
 static void CreatePropertyValue(
@@ -1064,9 +1140,14 @@ void KeyframeEffect::GetProperties(
       if (segment.mFromKey == segment.mToKey) {
         fromValue.mEasing.Reset();
       }
-      // The following won't fail since we have already allocated the capacity
-      // above.
-      propertyDetails.mValues.AppendElement(fromValue, mozilla::fallible);
+      // Even though we called SetCapacity before, this could fail, since we
+      // might add multiple elements to propertyDetails.mValues for an element
+      // of property.mSegments in the cases mentioned below.
+      if (!propertyDetails.mValues.AppendElement(fromValue,
+                                                 mozilla::fallible)) {
+        aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
+        return;
+      }
 
       // Normally we can ignore the to-value for this segment since it is
       // identical to the from-value from the next segment. However, we need
@@ -1082,7 +1163,11 @@ void KeyframeEffect::GetProperties(
         // last property value or before a sudden jump so we just drop the
         // easing property altogether.
         toValue.mEasing.Reset();
-        propertyDetails.mValues.AppendElement(toValue, mozilla::fallible);
+        if (!propertyDetails.mValues.AppendElement(toValue,
+                                                   mozilla::fallible)) {
+          aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
+          return;
+        }
       }
     }
 
@@ -1090,7 +1175,7 @@ void KeyframeEffect::GetProperties(
   }
 }
 
-void KeyframeEffect::GetKeyframes(JSContext*& aCx, nsTArray<JSObject*>& aResult,
+void KeyframeEffect::GetKeyframes(JSContext* aCx, nsTArray<JSObject*>& aResult,
                                   ErrorResult& aRv) const {
   MOZ_ASSERT(aResult.IsEmpty());
   MOZ_ASSERT(!aRv.Failed());
@@ -1140,6 +1225,8 @@ void KeyframeEffect::GetKeyframes(JSContext*& aCx, nsTArray<JSObject*>& aResult,
       keyframe.mTimingFunction.ref().AppendToString(keyframeDict.mEasing);
     }  // else if null, leave easing as its default "linear".
 
+    // With the pref off (i.e. dom.animations-api.compositing.enabled:false),
+    // the dictionary-to-JS conversion will skip this member entirely.
     keyframeDict.mComposite = keyframe.mComposite;
 
     JS::Rooted<JS::Value> keyframeJSValue(aCx);
@@ -1227,6 +1314,46 @@ KeyframeEffect::OverflowRegionRefreshInterval() {
   return kOverflowRegionRefreshInterval;
 }
 
+static bool IsDefinitivelyInvisibleDueToOpacity(const nsIFrame& aFrame) {
+  if (!aFrame.Style()->IsInOpacityZeroSubtree()) {
+    return false;
+  }
+
+  // Find the root of the opacity: 0 subtree.
+  const nsIFrame* root = &aFrame;
+  while (true) {
+    auto* parent = root->GetInFlowParent();
+    if (!parent || !parent->Style()->IsInOpacityZeroSubtree()) {
+      break;
+    }
+    root = parent;
+  }
+
+  MOZ_ASSERT(root && root->Style()->IsInOpacityZeroSubtree());
+
+  // If aFrame is the root of the opacity: zero subtree, we can't prove we can
+  // optimize it away, because it may have an opacity animation itself.
+  if (root == &aFrame) {
+    return false;
+  }
+
+  // Even if we're in an opacity: zero subtree, if the root of the subtree may
+  // have an opacity animation, we can't optimize us away, as we may become
+  // visible ourselves.
+  return !root->HasAnimationOfOpacity();
+}
+
+static bool CanOptimizeAwayDueToOpacity(const KeyframeEffect& aEffect,
+                                        const nsIFrame& aFrame) {
+  if (!aFrame.Style()->IsInOpacityZeroSubtree()) {
+    return false;
+  }
+  if (IsDefinitivelyInvisibleDueToOpacity(aFrame)) {
+    return true;
+  }
+  return !aEffect.HasOpacityChange() && !aFrame.HasAnimationOfOpacity();
+}
+
 bool KeyframeEffect::CanThrottleIfNotVisible(nsIFrame& aFrame) const {
   // Unless we are newly in-effect, we can throttle the animation if the
   // animation is paint only and the target frame is out of view or the document
@@ -1242,8 +1369,13 @@ bool KeyframeEffect::CanThrottleIfNotVisible(nsIFrame& aFrame) const {
 
   const bool isVisibilityHidden =
       !aFrame.IsVisibleOrMayHaveVisibleDescendants();
-  if ((!isVisibilityHidden || HasVisibilityChange()) &&
-      !aFrame.IsScrolledOutOfView()) {
+  const bool canOptimizeAwayVisibility =
+      isVisibilityHidden && !HasVisibilityChange();
+
+  const bool invisible = canOptimizeAwayVisibility ||
+                         CanOptimizeAwayDueToOpacity(*this, aFrame) ||
+                         aFrame.IsScrolledOutOfView();
+  if (!invisible) {
     return false;
   }
 
@@ -1302,7 +1434,7 @@ bool KeyframeEffect::CanThrottle() const {
                "The property should be able to run on the compositor");
     if (!effectSet) {
       effectSet =
-          EffectSet::GetEffectSet(mTarget->mElement, mTarget->mPseudoType);
+          EffectSet::GetEffectSet(mTarget.mElement, mTarget.mPseudoType);
       MOZ_ASSERT(effectSet,
                  "CanThrottle should be called on an effect "
                  "associated with a target element");
@@ -1338,7 +1470,7 @@ bool KeyframeEffect::CanThrottleOverflowChanges(const nsIFrame& aFrame) const {
   TimeStamp now = aFrame.PresContext()->RefreshDriver()->MostRecentRefresh();
 
   EffectSet* effectSet =
-      EffectSet::GetEffectSet(mTarget->mElement, mTarget->mPseudoType);
+      EffectSet::GetEffectSet(mTarget.mElement, mTarget.mPseudoType);
   MOZ_ASSERT(effectSet,
              "CanOverflowTransformChanges is expected to be called"
              " on an effect in an effect set");
@@ -1367,7 +1499,7 @@ bool KeyframeEffect::CanThrottleOverflowChangesInScrollable(
 
   // If we don't show scrollbars and have no intersection observers, we don't
   // care about overflow.
-  if (LookAndFeel::GetInt(LookAndFeel::eIntID_ShowHideScrollbars) == 0 &&
+  if (LookAndFeel::GetInt(LookAndFeel::IntID::ShowHideScrollbars) == 0 &&
       !hasIntersectionObservers) {
     return true;
   }
@@ -1415,16 +1547,16 @@ nsIFrame* KeyframeEffect::GetPrimaryFrame() const {
     return frame;
   }
 
-  if (mTarget->mPseudoType == PseudoStyleType::before) {
-    frame = nsLayoutUtils::GetBeforeFrame(mTarget->mElement);
-  } else if (mTarget->mPseudoType == PseudoStyleType::after) {
-    frame = nsLayoutUtils::GetAfterFrame(mTarget->mElement);
-  } else if (mTarget->mPseudoType == PseudoStyleType::marker) {
-    frame = nsLayoutUtils::GetMarkerFrame(mTarget->mElement);
+  if (mTarget.mPseudoType == PseudoStyleType::before) {
+    frame = nsLayoutUtils::GetBeforeFrame(mTarget.mElement);
+  } else if (mTarget.mPseudoType == PseudoStyleType::after) {
+    frame = nsLayoutUtils::GetAfterFrame(mTarget.mElement);
+  } else if (mTarget.mPseudoType == PseudoStyleType::marker) {
+    frame = nsLayoutUtils::GetMarkerFrame(mTarget.mElement);
   } else {
-    frame = mTarget->mElement->GetPrimaryFrame();
-    MOZ_ASSERT(mTarget->mPseudoType == PseudoStyleType::NotPseudo,
-               "unknown mTarget->mPseudoType");
+    frame = mTarget.mElement->GetPrimaryFrame();
+    MOZ_ASSERT(mTarget.mPseudoType == PseudoStyleType::NotPseudo,
+               "unknown mTarget.mPseudoType");
   }
 
   return frame;
@@ -1434,7 +1566,7 @@ Document* KeyframeEffect::GetRenderedDocument() const {
   if (!mTarget) {
     return nullptr;
   }
-  return mTarget->mElement->GetComposedDoc();
+  return mTarget.mElement->GetComposedDoc();
 }
 
 PresShell* KeyframeEffect::GetPresShell() const {
@@ -1516,7 +1648,7 @@ bool KeyframeEffect::ShouldBlockAsyncTransformAnimations(
     const nsIFrame* aFrame, const nsCSSPropertyIDSet& aPropertySet,
     AnimationPerformanceWarning::Type& aPerformanceWarning /* out */) const {
   EffectSet* effectSet =
-      EffectSet::GetEffectSet(mTarget->mElement, mTarget->mPseudoType);
+      EffectSet::GetEffectSet(mTarget.mElement, mTarget.mPseudoType);
   // The various transform properties ('transform', 'scale' etc.) get combined
   // on the compositor.
   //
@@ -1535,6 +1667,10 @@ bool KeyframeEffect::ShouldBlockAsyncTransformAnimations(
     return true;
   }
 
+  const bool enableMainthreadSynchronizationWithGeometricAnimations =
+      StaticPrefs::
+          dom_animations_mainthread_synchronization_with_geometric_animations();
+
   for (const AnimationProperty& property : mProperties) {
     // If there is a property for animations level that is overridden by
     // !important rules, it should not block other animations from running
@@ -1551,7 +1687,8 @@ bool KeyframeEffect::ShouldBlockAsyncTransformAnimations(
       continue;
     }
     // Check for geometric properties
-    if (IsGeometricProperty(property.mProperty)) {
+    if (enableMainthreadSynchronizationWithGeometricAnimations &&
+        IsGeometricProperty(property.mProperty)) {
       aPerformanceWarning =
           AnimationPerformanceWarning::Type::TransformWithGeometricProperties;
       return true;
@@ -1587,7 +1724,7 @@ void KeyframeEffect::SetPerformanceWarning(
     if (!curr.HasProperty(property.mProperty)) {
       continue;
     }
-    property.SetPerformanceWarning(aWarning, mTarget->mElement);
+    property.SetPerformanceWarning(aWarning, mTarget.mElement);
     curr.RemoveProperty(property.mProperty);
     if (curr.IsEmpty()) {
       return;
@@ -1604,7 +1741,7 @@ KeyframeEffect::CreateComputedStyleForAnimationValue(
              "with a valid ComputedStyle");
 
   Element* elementForResolve = EffectCompositor::GetElementToRestyle(
-      mTarget->mElement, mTarget->mPseudoType);
+      mTarget.mElement, mTarget.mPseudoType);
   // The element may be null if, for example, we target a pseudo-element that no
   // longer exists.
   if (!elementForResolve) {
@@ -1622,7 +1759,7 @@ void KeyframeEffect::CalculateCumulativeChangeHint(
   mNeedsStyleData = false;
 
   nsPresContext* presContext =
-      mTarget ? nsContentUtils::GetContextForContent(mTarget->mElement)
+      mTarget ? nsContentUtils::GetContextForContent(mTarget.mElement)
               : nullptr;
   if (!presContext) {
     // Change hints make no sense if we're not rendered.
@@ -1715,7 +1852,7 @@ void KeyframeEffect::SetAnimation(Animation* aAnimation) {
 }
 
 bool KeyframeEffect::CanIgnoreIfNotVisible() const {
-  if (!AnimationUtils::IsOffscreenThrottlingEnabled()) {
+  if (!StaticPrefs::dom_animations_offscreen_throttling()) {
     return false;
   }
 
@@ -1731,7 +1868,7 @@ void KeyframeEffect::MarkCascadeNeedsUpdate() {
   }
 
   EffectSet* effectSet =
-      EffectSet::GetEffectSet(mTarget->mElement, mTarget->mPseudoType);
+      EffectSet::GetEffectSet(mTarget.mElement, mTarget.mPseudoType);
   if (!effectSet) {
     return;
   }
@@ -1785,14 +1922,11 @@ bool KeyframeEffect::ContainsAnimatedScale(const nsIFrame* aFrame) const {
     }
 
     AnimationValue baseStyle = BaseStyle(prop.mProperty);
-    if (baseStyle.IsNull()) {
-      // If we failed to get the base style, we consider it has scale value
-      // here just to be safe.
-      return true;
-    }
-    gfx::Size size = baseStyle.GetScaleValue(aFrame);
-    if (size != gfx::Size(1.0f, 1.0f)) {
-      return true;
+    if (!baseStyle.IsNull()) {
+      gfx::Size size = baseStyle.GetScaleValue(aFrame);
+      if (size != gfx::Size(1.0f, 1.0f)) {
+        return true;
+      }
     }
 
     // This is actually overestimate because there are some cases that combining
@@ -1825,7 +1959,7 @@ void KeyframeEffect::UpdateEffectSet(EffectSet* aEffectSet) const {
   EffectSet* effectSet =
       aEffectSet
           ? aEffectSet
-          : EffectSet::GetEffectSet(mTarget->mElement, mTarget->mPseudoType);
+          : EffectSet::GetEffectSet(mTarget.mElement, mTarget.mPseudoType);
   if (!effectSet) {
     return;
   }
@@ -1878,6 +2012,7 @@ KeyframeEffect::MatchForCompositor KeyframeEffect::IsMatchForCompositor(
   // If we know that the animation is not visible, we don't need to send the
   // animation to the compositor.
   if (!aFrame->IsVisibleOrMayHaveVisibleDescendants() ||
+      IsDefinitivelyInvisibleDueToOpacity(*aFrame) ||
       aFrame->IsScrolledOutOfView()) {
     return KeyframeEffect::MatchForCompositor::NoAndBlockThisProperty;
   }
@@ -1899,6 +2034,13 @@ KeyframeEffect::MatchForCompositor KeyframeEffect::IsMatchForCompositor(
     }
   }
 
+  // We can't run this background color animation on the compositor if there
+  // is any `current-color` keyframe.
+  if (mHasCurrentColor) {
+    aPerformanceWarning = AnimationPerformanceWarning::Type::HasCurrentColor;
+    return KeyframeEffect::MatchForCompositor::NoAndBlockThisProperty;
+  }
+
   return mAnimation->IsPlaying() ? KeyframeEffect::MatchForCompositor::Yes
                                  : KeyframeEffect::MatchForCompositor::IfNeeded;
 }

dom/animation/KeyframeEffect.h

@@ -37,7 +37,6 @@ class nsIFrame;
 namespace mozilla {
 
 class AnimValuesStyleRule;
-enum class PseudoStyleType : uint8_t;
 class ErrorResult;
 struct AnimationRule;
 struct TimingParams;
@@ -46,9 +45,7 @@ class ComputedStyle;
 class PresShell;
 
 namespace dom {
-class ElementOrCSSPseudoElement;
 class GlobalObject;
-class OwningElementOrCSSPseudoElement;
 class UnrestrictedDoubleOrKeyframeAnimationOptions;
 class UnrestrictedDoubleOrKeyframeEffectOptions;
 enum class IterationCompositeOperation : uint8_t;
@@ -102,8 +99,6 @@ struct AnimationProperty {
                              const dom::Element* aElement);
 };
 
-struct ElementPropertyTransition;
-
 namespace dom {
 
 class Animation;
@@ -111,8 +106,7 @@ class Document;
 
 class KeyframeEffect : public AnimationEffect {
  public:
-  KeyframeEffect(Document* aDocument,
-                 const Maybe<OwningAnimationTarget>& aTarget,
+  KeyframeEffect(Document* aDocument, OwningAnimationTarget&& aTarget,
                  TimingParams&& aTiming, const KeyframeEffectParams& aOptions);
 
   NS_DECL_ISUPPORTS_INHERITED
@@ -126,8 +120,7 @@ class KeyframeEffect : public AnimationEffect {
 
   // KeyframeEffect interface
   static already_AddRefed<KeyframeEffect> Constructor(
-      const GlobalObject& aGlobal,
-      const Nullable<ElementOrCSSPseudoElement>& aTarget,
+      const GlobalObject& aGlobal, Element* aTarget,
       JS::Handle<JSObject*> aKeyframes,
       const UnrestrictedDoubleOrKeyframeEffectOptions& aOptions,
       ErrorResult& aRv);
@@ -139,28 +132,37 @@ class KeyframeEffect : public AnimationEffect {
   // for use with for Animatable.animate.
   // Not exposed to content.
   static already_AddRefed<KeyframeEffect> Constructor(
-      const GlobalObject& aGlobal,
-      const Nullable<ElementOrCSSPseudoElement>& aTarget,
+      const GlobalObject& aGlobal, Element* aTarget,
       JS::Handle<JSObject*> aKeyframes,
       const UnrestrictedDoubleOrKeyframeAnimationOptions& aOptions,
       ErrorResult& aRv);
 
-  void GetTarget(Nullable<OwningElementOrCSSPseudoElement>& aRv) const;
-  Maybe<NonOwningAnimationTarget> GetTarget() const {
-    Maybe<NonOwningAnimationTarget> result;
-    if (mTarget) {
-      result.emplace(*mTarget);
-    }
-    return result;
+  already_AddRefed<Element> GetTarget() const {
+    RefPtr<Element> ret = mTarget.mElement;
+    return ret.forget();
   }
-  // This method calls GetTargetComputedStyle which is not safe to use when
+  NonOwningAnimationTarget GetAnimationTarget() const {
+    return NonOwningAnimationTarget(mTarget.mElement, mTarget.mPseudoType);
+  }
+  void GetPseudoElement(nsAString& aRetVal) const {
+    if (mTarget.mPseudoType == PseudoStyleType::NotPseudo) {
+      SetDOMStringToNull(aRetVal);
+      return;
+    }
+    aRetVal = nsCSSPseudoElements::PseudoTypeAsString(mTarget.mPseudoType);
+  }
+
+  // These two setters call GetTargetComputedStyle which is not safe to use when
   // we are in the middle of updating style. If we need to use this when
   // updating style, we should pass the ComputedStyle into this method and use
   // that to update the properties rather than calling
   // GetComputedStyle.
-  void SetTarget(const Nullable<ElementOrCSSPseudoElement>& aTarget);
+  void SetTarget(Element* aTarget) {
+    UpdateTarget(aTarget, mTarget.mPseudoType);
+  }
+  void SetPseudoElement(const nsAString& aPseudoElement, ErrorResult& aRv);
 
-  void GetKeyframes(JSContext*& aCx, nsTArray<JSObject*>& aResult,
+  void GetKeyframes(JSContext* aCx, nsTArray<JSObject*>& aResult,
                     ErrorResult& aRv) const;
   void GetProperties(nsTArray<AnimationPropertyDetails>& aProperties,
                      ErrorResult& aRv) const;
@@ -176,11 +178,15 @@ class KeyframeEffect : public AnimationEffect {
   void NotifyAnimationTimingUpdated(PostRestyleMode aPostRestyle);
   void RequestRestyle(EffectCompositor::RestyleType aRestyleType);
   void SetAnimation(Animation* aAnimation) override;
-  void SetKeyframes(JSContext* aContext, JS::Handle<JSObject*> aKeyframes,
-                    ErrorResult& aRv);
+  virtual void SetKeyframes(JSContext* aContext,
+                            JS::Handle<JSObject*> aKeyframes, ErrorResult& aRv);
   void SetKeyframes(nsTArray<Keyframe>&& aKeyframes,
                     const ComputedStyle* aStyle);
 
+  // Replace the start value of the transition. This is used for updating
+  // transitions running on the compositor.
+  void ReplaceTransitionStartValue(AnimationValue&& aStartValue);
+
   // Returns the set of properties affected by this effect regardless of
   // whether any of these properties is overridden by an !important rule.
   nsCSSPropertyIDSet GetPropertySet() const;
@@ -277,7 +283,7 @@ class KeyframeEffect : public AnimationEffect {
       AnimationPerformanceWarning::Type& aPerformanceWarning /* out */) const;
   bool HasGeometricProperties() const;
   bool AffectsGeometry() const override {
-    return GetTarget() && HasGeometricProperties();
+    return mTarget && HasGeometricProperties();
   }
 
   Document* GetRenderedDocument() const;
@@ -341,16 +347,16 @@ class KeyframeEffect : public AnimationEffect {
       const Nullable<double>& aProgressOnLastCompose,
       uint64_t aCurrentIterationOnLastCompose);
 
+  bool HasOpacityChange() const {
+    return mCumulativeChangeHint & nsChangeHint_UpdateOpacityLayer;
+  }
+
  protected:
   ~KeyframeEffect() override = default;
 
-  static Maybe<OwningAnimationTarget> ConvertTarget(
-      const Nullable<ElementOrCSSPseudoElement>& aTarget);
-
   template <class OptionsType>
   static already_AddRefed<KeyframeEffect> ConstructKeyframeEffect(
-      const GlobalObject& aGlobal,
-      const Nullable<ElementOrCSSPseudoElement>& aTarget,
+      const GlobalObject& aGlobal, Element* aTarget,
       JS::Handle<JSObject*> aKeyframes, const OptionsType& aOptions,
       ErrorResult& aRv);
 
@@ -359,6 +365,9 @@ class KeyframeEffect : public AnimationEffect {
   // needed.
   nsTArray<AnimationProperty> BuildProperties(const ComputedStyle* aStyle);
 
+  // Helper for SetTarget() and SetPseudoElement().
+  void UpdateTarget(Element* aElement, PseudoStyleType aPseudoType);
+
   // This effect is registered with its target element so long as:
   //
   // (a) It has a target element, and
@@ -397,7 +406,7 @@ class KeyframeEffect : public AnimationEffect {
                        const ComputedStyle* aComputedValues,
                        RefPtr<ComputedStyle>& aBaseComputedValues);
 
-  Maybe<OwningAnimationTarget> mTarget;
+  OwningAnimationTarget mTarget;
 
   KeyframeEffectParams mEffectOptions;
 
@@ -432,6 +441,9 @@ class KeyframeEffect : public AnimationEffect {
   // if our properties haven't changed.
   bool mNeedsStyleData = false;
 
+  // True if there is any current-color for background color in this keyframes.
+  bool mHasCurrentColor = false;
+
   // The non-animated values for properties in this effect that contain at
   // least one animation value that is composited with the underlying value
   // (i.e. it uses the additive or accumulate composite mode).

dom/animation/KeyframeEffectParams.h

@@ -6,6 +6,7 @@
 #define mozilla_KeyframeEffectParams_h
 
 #include "mozilla/dom/KeyframeEffectBinding.h"  // IterationCompositeOperation
+#include "mozilla/PseudoStyleType.h"            // PseudoStyleType
 
 namespace mozilla {
 
@@ -13,6 +14,7 @@ struct KeyframeEffectParams {
   dom::IterationCompositeOperation mIterationComposite =
       dom::IterationCompositeOperation::Replace;
   dom::CompositeOperation mComposite = dom::CompositeOperation::Replace;
+  PseudoStyleType mPseudoType = PseudoStyleType::NotPseudo;
 };
 
 }  // namespace mozilla

dom/animation/KeyframeUtils.cpp

@@ -4,33 +4,35 @@
 
 #include "mozilla/KeyframeUtils.h"
 
+#include <algorithm>  // For std::stable_sort, std::min
+
+#include "js/ForOfIterator.h"  // For JS::ForOfIterator
+#include "jsapi.h"             // For most JSAPI
 #include "mozilla/ComputedStyle.h"
 #include "mozilla/ErrorResult.h"
 #include "mozilla/Move.h"
 #include "mozilla/RangedArray.h"
-#include "mozilla/ServoBindings.h"
 #include "mozilla/ServoBindingTypes.h"
+#include "mozilla/ServoBindings.h"
 #include "mozilla/ServoCSSParser.h"
-#include "mozilla/StyleAnimationValue.h"
 #include "mozilla/StaticPrefs_dom.h"
+#include "mozilla/StyleAnimationValue.h"
 #include "mozilla/TimingParams.h"
 #include "mozilla/dom/BaseKeyframeTypesBinding.h"  // For FastBaseKeyframe etc.
+#include "mozilla/dom/BindingCallContext.h"
 #include "mozilla/dom/Document.h"  // For Document::AreWebAnimationsImplicitKeyframesEnabled
 #include "mozilla/dom/Element.h"
-#include "mozilla/dom/KeyframeEffectBinding.h"
 #include "mozilla/dom/KeyframeEffect.h"  // For PropertyValuesPair etc.
+#include "mozilla/dom/KeyframeEffectBinding.h"
 #include "mozilla/dom/Nullable.h"
-#include "jsapi.h"             // For most JSAPI
-#include "js/ForOfIterator.h"  // For JS::ForOfIterator
-#include "nsClassHashtable.h"
-#include "nsContentUtils.h"  // For GetContextForContent
 #include "nsCSSPropertyIDSet.h"
 #include "nsCSSProps.h"
 #include "nsCSSPseudoElements.h"  // For PseudoStyleType
+#include "nsClassHashtable.h"
+#include "nsContentUtils.h"  // For GetContextForContent
 #include "nsIScriptError.h"
 #include "nsPresContextInlines.h"
 #include "nsTArray.h"
-#include <algorithm>  // For std::stable_sort, std::min
 
 using mozilla::dom::Nullable;
 
@@ -380,7 +382,10 @@ static bool ConvertKeyframeSequence(JSContext* aCx, dom::Document* aDocument,
                                     const char* aContext,
                                     nsTArray<Keyframe>& aResult) {
   JS::Rooted<JS::Value> value(aCx);
-  ErrorResult parseEasingResult;
+  // Parsing errors should only be reported after we have finished iterating
+  // through all values. If we have any early returns while iterating, we should
+  // ignore parsing errors.
+  IgnoredErrorResult parseEasingResult;
 
   for (;;) {
     bool done;
@@ -395,16 +400,20 @@ static bool ConvertKeyframeSequence(JSContext* aCx, dom::Document* aDocument,
     // value).
     if (!value.isObject() && !value.isNullOrUndefined()) {
       dom::ThrowErrorMessage<dom::MSG_NOT_OBJECT>(
-          aCx,
-          nsPrintfCString("%sElement of sequence<Keyframe> argument", aContext)
-              .get());
+          aCx, aContext, "Element of sequence<Keyframe> argument");
       return false;
     }
 
     // Convert the JS value into a BaseKeyframe dictionary value.
     dom::binding_detail::FastBaseKeyframe keyframeDict;
-    if (!keyframeDict.Init(aCx, value,
+    dom::BindingCallContext callCx(aCx, aContext);
+    if (!keyframeDict.Init(callCx, value,
                            "Element of sequence<Keyframe> argument")) {
+      // This may happen if the value type of the member of BaseKeyframe is
+      // invalid. e.g. `offset` only accept a double value, so if we provide a
+      // string, we enter this branch.
+      // Besides, keyframeDict.Init() should throw a Type Error message already,
+      // so we don't have to do it again.
       return false;
     }
 
@@ -412,6 +421,7 @@ static bool ConvertKeyframeSequence(JSContext* aCx, dom::Document* aDocument,
     if (!keyframe) {
       return false;
     }
+
     if (!keyframeDict.mOffset.IsNull()) {
       keyframe->mOffset.emplace(keyframeDict.mOffset.Value());
     }
@@ -969,8 +979,8 @@ static void GetKeyframeListFromPropertyIndexedKeyframe(
   // Convert the object to a property-indexed keyframe dictionary to
   // get its explicit dictionary members.
   dom::binding_detail::FastBasePropertyIndexedKeyframe keyframeDict;
-  if (!keyframeDict.Init(aCx, aValue, "BasePropertyIndexedKeyframe argument",
-                         false)) {
+  // XXXbz Pass in the method name from callers and set up a BindingCallContext?
+  if (!keyframeDict.Init(aCx, aValue, "BasePropertyIndexedKeyframe argument")) {
     aRv.Throw(NS_ERROR_FAILURE);
     return;
   }

dom/animation/PendingAnimationTracker.h

@@ -75,7 +75,7 @@ class PendingAnimationTracker final {
   void MarkAnimationsThatMightNeedSynchronization();
 
  private:
-  ~PendingAnimationTracker() {}
+  ~PendingAnimationTracker() = default;
 
   void EnsurePaintIsScheduled();
 

dom/animation/TimingParams.cpp

@@ -46,7 +46,8 @@ TimingParams TimingParams::FromOptionsType(const OptionsType& aOptions,
       result.mDuration.emplace(
           StickyTimeDuration::FromMilliseconds(durationInMs));
     } else {
-      aRv.Throw(NS_ERROR_DOM_TYPE_ERR);
+      nsPrintfCString error("Duration value %g is less than 0", durationInMs);
+      aRv.ThrowTypeError(error);
       return result;
     }
     result.Update();
@@ -196,7 +197,8 @@ Maybe<ComputedTimingFunction> TimingParams::ParseEasing(
   nsTimingFunction timingFunction;
   RefPtr<URLExtraData> url = ServoCSSParser::GetURLExtraData(aDocument);
   if (!ServoCSSParser::ParseEasing(aEasing, url, timingFunction)) {
-    aRv.ThrowTypeError<dom::MSG_INVALID_EASING_ERROR>(aEasing);
+    aRv.ThrowTypeError<dom::MSG_INVALID_EASING_ERROR>(
+        NS_ConvertUTF16toUTF8(aEasing));
     return Nothing();
   }
 

dom/animation/TimingParams.h

@@ -6,6 +6,7 @@
 #define mozilla_TimingParams_h
 
 #include "nsStringFwd.h"
+#include "nsPrintfCString.h"
 #include "mozilla/dom/Nullable.h"
 #include "mozilla/dom/UnionTypes.h"  // For OwningUnrestrictedDoubleOrString
 #include "mozilla/ComputedTimingFunction.h"
@@ -88,27 +89,33 @@ struct TimingParams {
       if (durationInMs >= 0) {
         result.emplace(StickyTimeDuration::FromMilliseconds(durationInMs));
       } else {
-        aRv.ThrowTypeError<dom::MSG_ENFORCE_RANGE_OUT_OF_RANGE>(
-            NS_LITERAL_STRING("duration"));
+        nsPrintfCString err("Duration (%g) must be nonnegative", durationInMs);
+        aRv.ThrowTypeError(err);
       }
     } else if (!aDuration.GetAsString().EqualsLiteral("auto")) {
       aRv.ThrowTypeError<dom::MSG_INVALID_DURATION_ERROR>(
-          aDuration.GetAsString());
+          NS_ConvertUTF16toUTF8(aDuration.GetAsString()));
     }
     return result;
   }
 
   static void ValidateIterationStart(double aIterationStart, ErrorResult& aRv) {
     if (aIterationStart < 0) {
-      aRv.ThrowTypeError<dom::MSG_ENFORCE_RANGE_OUT_OF_RANGE>(
-          NS_LITERAL_STRING("iterationStart"));
+      nsPrintfCString err("Iteration start (%g) must not be negative",
+                          aIterationStart);
+      aRv.ThrowTypeError(err);
     }
   }
 
   static void ValidateIterations(double aIterations, ErrorResult& aRv) {
-    if (IsNaN(aIterations) || aIterations < 0) {
-      aRv.ThrowTypeError<dom::MSG_ENFORCE_RANGE_OUT_OF_RANGE>(
-          NS_LITERAL_STRING("iterations"));
+    if (IsNaN(aIterations)) {
+      aRv.ThrowTypeError("Iterations must not be NaN");
+      return;
+    }
+
+    if (aIterations < 0) {
+      nsPrintfCString err("Iterations (%g) must not be negative", aIterations);
+      aRv.ThrowTypeError(err);
     }
   }
 
@@ -152,6 +159,10 @@ struct TimingParams {
     mDuration = std::move(aDuration);
     Update();
   }
+  void SetDuration(const Maybe<StickyTimeDuration>& aDuration) {
+    mDuration = aDuration;
+    Update();
+  }
   const Maybe<StickyTimeDuration>& Duration() const { return mDuration; }
 
   void SetDelay(const TimeDuration& aDelay) {

dom/animation/moz.build

@@ -12,7 +12,9 @@ EXPORTS.mozilla.dom += [
     'Animation.h',
     'AnimationEffect.h',
     'AnimationTimeline.h',
+    'CSSAnimation.h',
     'CSSPseudoElement.h',
+    'CSSTransition.h',
     'DocumentTimeline.h',
     'KeyframeEffect.h',
 ]
@@ -45,7 +47,9 @@ UNIFIED_SOURCES += [
     'AnimationTimeline.cpp',
     'AnimationUtils.cpp',
     'ComputedTimingFunction.cpp',
+    'CSSAnimation.cpp',
     'CSSPseudoElement.cpp',
+    'CSSTransition.cpp',
     'DocumentTimeline.cpp',
     'EffectCompositor.cpp',
     'EffectSet.cpp',
@@ -61,4 +65,6 @@ LOCAL_INCLUDES += [
     '/layout/style',
 ]
 
+include('/ipc/chromium/chromium-config.mozbuild')
+
 FINAL_LIBRARY = 'xul'

dom/animation/test/chrome/test_animation_observers_async.html

@@ -502,13 +502,14 @@ promise_test(t => {
   var childBAnimations = childB.getAnimations();
 
   var divBeforeAnimations =
-    docAnims.filter(x => (x.effect.target.element == div &&
-                          x.effect.target.type == "::before"));
+    docAnims.filter(x => (x.effect.target == div &&
+                          x.effect.pseudoElement == "::before"));
   var divAfterAnimations =
-    docAnims.filter(x => (x.effect.target.element == div &&
-                          x.effect.target.type == "::after"));
+    docAnims.filter(x => (x.effect.target == div &&
+                          x.effect.pseudoElement == "::after"));
   var childBPseudoAnimations =
-    docAnims.filter(x => x.effect.target.element == childB);
+    docAnims.filter(x => (x.effect.target == childB &&
+                          x.effect.pseudoElement == "::before"));
 
   var seekRecords;
   // The order in which we get the corresponding records is currently

dom/animation/test/chrome/test_animation_observers_sync.html

@@ -74,21 +74,6 @@ function assert_equals_records(actual, expected, desc) {
   }
 }
 
-// Create a pseudo element
-function createPseudo(test, element, type) {
-  addStyle(test, { '@keyframes anim': '',
-                   ['.pseudo::' + type]: 'animation: anim 10s; ' +
-                                         'content: \'\';'  });
-  element.classList.add('pseudo');
-  var anims = document.getAnimations();
-  assert_true(anims.length >= 1);
-  var anim = anims[anims.length - 1];
-  assert_equals(anim.effect.target.element, element);
-  assert_equals(anim.effect.target.type, '::' + type);
-  anim.cancel();
-  return anim.effect.target;
-}
-
 function runTest() {
   [ { subtree: false },
     { subtree: true }
@@ -1518,10 +1503,11 @@ function runTest() {
 
   test(t => {
     var div = addDiv(t);
-    var pseudoTarget = createPseudo(t, div, 'before');
     var observer = setupSynchronousObserver(t, div, true);
 
-    var anim = pseudoTarget.animate({ opacity: [ 0, 1 ] }, 200 * MS_PER_SEC);
+    var anim = div.animate({ opacity: [ 0, 1 ] },
+                           { duration: 200 * MS_PER_SEC,
+                             pseudoElement: '::before' });
 
     assert_equals_records(observer.takeRecords(),
       [{ added: [anim], changed: [], removed: [] }],
@@ -1561,13 +1547,13 @@ function runTest() {
 
   test(t => {
     var div = addDiv(t);
-    var pseudoTarget = createPseudo(t, div, 'before');
     var observer = setupSynchronousObserver(t, div, false);
 
     var anim = div.animate({ opacity: [ 0, 1 ] },
                            { duration: 100 * MS_PER_SEC });
-    var pAnim = pseudoTarget.animate({ opacity: [ 0, 1 ] },
-                                     { duration: 100 * MS_PER_SEC });
+    var pAnim = div.animate({ opacity: [ 0, 1 ] },
+                            { duration: 100 * MS_PER_SEC,
+                              pseudoElement: "::before" });
 
     assert_equals_records(observer.takeRecords(),
       [{ added: [anim], changed: [], removed: [] }],

dom/animation/test/chrome/test_animation_performance_warning.html

@@ -1644,6 +1644,27 @@ function testImportantRuleOverride() {
      'compositor because any of the properties has important rules');
 }
 
+function testCurrentColor() {
+  if (SpecialPowers.DOMWindowUtils.layerManagerType == 'WebRender') {
+    return; // skip this test until bug 1510030 landed.
+  }
+  promise_test(async t => {
+    const animation = addDivAndAnimate(t, { class: 'compositable' },
+                                       { backgroundColor: [ 'currentColor',
+                                                            'red' ] },
+                                       100 * MS_PER_SEC);
+    await waitForPaints();
+
+    assert_animation_property_state_equals(
+      animation.effect.getProperties(),
+      [ { property: 'background-color',
+          runningOnCompositor: false,
+          warning: 'CompositorAnimationWarningHasCurrentColor'
+      } ]);
+  }, 'Background color animations with `current-color` don\'t run on the '
+     + 'compositor');
+}
+
 function start() {
   var bundleService = SpecialPowers.Cc['@mozilla.org/intl/stringbundle;1']
     .getService(SpecialPowers.Ci.nsIStringBundleService);
@@ -1663,6 +1684,7 @@ function start() {
   testTooLargeFrame();
   testTransformSVG();
   testImportantRuleOverride();
+  testCurrentColor();
 
   promise_test(async t => {
     var div = addDiv(t, { class: 'compositable',

dom/animation/test/crashtests/1585770.html

@@ -0,0 +1,22 @@
+<html class="reftest-wait">
+<script>
+function start () {
+  const kf_effect =
+      new KeyframeEffect(document.documentElement,
+                         { opacity: ['', '1'] },
+                         { easing: 'step-end',
+                           duration: 10000 } );
+  const copy = new KeyframeEffect(kf_effect);
+  const animation = new Animation(copy);
+
+  animation.reverse();
+  document.documentElement.getBoundingClientRect();
+
+  requestAnimationFrame(() => {
+    document.documentElement.classList.remove("reftest-wait");
+  });
+}
+
+document.addEventListener('DOMContentLoaded', start);
+</script>
+</html>

dom/animation/test/crashtests/1604500-1.html

@@ -0,0 +1,24 @@
+<!doctype html>
+<html>
+<head>
+<script>
+function start () {
+  const keyframe = new KeyframeEffect(undefined, {});
+  const animation = new Animation(keyframe, undefined);
+  // Make animation run backwards...
+  animation.playbackRate = -100;
+  // But then set the current time to the future so it becomes "current"...
+  animation.currentTime = 2055;
+  // After updating the playback rate to zero, however, it should no longer
+  // be "current" (and this takes effect immediately because |animation| is
+  // paused)...
+  animation.updatePlaybackRate(0);
+  // Now update the target and hope nothing goes wrong...
+  keyframe.target = div;
+}
+
+document.addEventListener('DOMContentLoaded', start)
+</script>
+</head>
+<div id=div></div>
+</html>

dom/animation/test/crashtests/1611847.html

@@ -0,0 +1,23 @@
+<html>
+<head>
+  <style>
+    * {
+      transition-duration: 2s;
+    }
+  </style>
+  <script>
+    function start () {
+      const element = document.createElementNS('', 's');
+      const effect = new KeyframeEffect(document.documentElement, {}, 196);
+      document.documentElement.setAttribute('style', 'padding-left:3');
+      effect.updateTiming({ 'delay': 2723 });
+      const animations = document.getAnimations();
+      animations[0].effect = effect;
+      animations[0].updatePlaybackRate(-129);
+      effect.target = element;
+    }
+
+    document.addEventListener('DOMContentLoaded', start);
+  </script>
+</head>
+</html>

dom/animation/test/crashtests/1612891-1.html

@@ -0,0 +1,15 @@
+<html>
+<head>
+  <script>
+    function start() {
+      const element = document.createElement('img')
+      element.animate([
+        { 'easing': '' },
+        { 'offset': 'o' },
+      ], {})
+    }
+
+    window.addEventListener('load', start)
+  </script>
+</head>
+</html>

dom/animation/test/crashtests/1612891-2.html

@@ -0,0 +1,15 @@
+<html>
+<head>
+  <script>
+    function start() {
+      const element = document.createElement('img')
+      element.animate([
+        { 'easing': '' },
+        123,
+      ], {})
+    }
+
+    window.addEventListener('load', start)
+  </script>
+</head>
+</html>

dom/animation/test/crashtests/1612891-3.html

@@ -0,0 +1,10 @@
+<html>
+<head>
+  <script>
+    document.addEventListener('DOMContentLoaded', () => {
+      const keyframe = new KeyframeEffect(document.documentElement, [{}], {})
+      keyframe.setKeyframes([{ 'easing': '' }, { 'offset': 'o', }])
+    })
+  </script>
+</head>
+</html>

dom/animation/test/crashtests/1633442.html

@@ -0,0 +1,15 @@
+<!doctype html>
+<html class="reftest-wait">
+<head>
+<script>
+  document.addEventListener('DOMContentLoaded', () => {
+    document.documentElement.style.setProperty('transition-duration', '3s', '')
+    document.documentElement.style.setProperty('rotate', '2deg', undefined)
+    document.documentElement.style.setProperty('-moz-outline-radius-topleft', '2%', '')
+    const [anim_1, anim_0] = document.documentElement.getAnimations({})
+    anim_1.effect = anim_0.effect
+    document.documentElement.classList.remove("reftest-wait");
+  })
+</script>
+</head>
+</html>

dom/animation/test/crashtests/1633486.html

@@ -0,0 +1,20 @@
+<!doctype html>
+<html>
+<head>
+  <script>
+    window.addEventListener('load', async () => {
+      const element = document.getElementById('target');
+      element.animate({
+        'all': ['initial']
+      }, {
+        'duration': 500,
+        'pseudoElement': '::marker',
+      })
+      element.hidden = false;
+    })
+  </script>
+</head>
+<ul>
+  <li id='target' hidden></li>
+</ul>
+</html>

dom/animation/test/crashtests/crashtests.list

@@ -44,3 +44,11 @@ pref(dom.animations-api.implicit-keyframes.enabled,true) load 1468294-1.html
 pref(dom.animations-api.implicit-keyframes.enabled,true) load 1467277-1.html
 load 1524480-1.html
 load 1575926.html
+pref(dom.animations-api.implicit-keyframes.enabled,true) load 1585770.html
+load 1604500-1.html
+pref(dom.animations-api.core.enabled,true) pref(dom.animations-api.getAnimations.enabled,true) load 1611847.html
+pref(dom.animations-api.core.enabled,true) load 1612891-1.html
+pref(dom.animations-api.core.enabled,true) load 1612891-2.html
+pref(dom.animations-api.core.enabled,true) load 1612891-3.html
+pref(dom.animations-api.core.enabled,true) pref(dom.animations-api.getAnimations.enabled,true) load 1633442.html
+pref(dom.animations-api.core.enabled,true) pref(dom.animations-api.implicit-keyframes.enabled,true) load 1633486.html

dom/animation/test/mochitest.ini

@@ -46,6 +46,7 @@ skip-if = (toolkit == 'android' && debug) || (os == 'win' && bits == 64) # Bug 1
 [mozilla/test_distance_of_transform.html]
 [mozilla/test_document_timeline_origin_time_range.html]
 [mozilla/test_hide_and_show.html]
+[mozilla/test_mainthread_synchronization_pref.html]
 [mozilla/test_moz_prefixed_properties.html]
 [mozilla/test_pending_animation_tracker.html]
 [mozilla/test_restyles.html]

dom/animation/test/mozilla/file_disable_animations_api_compositing.html

@@ -117,6 +117,21 @@ test(t => {
   );
 }, 'composite member is ignored on keyframes when using object notation');
 
+test(t => {
+  const anim = addDiv(t).animate(
+    { marginLeft: ['0px', '10px'] },
+    100 * MS_PER_SEC
+  );
+
+  for (let frame of anim.effect.getKeyframes()) {
+    assert_false(
+      'composite' in frame,
+      'The BaseComputedKeyframe.composite member is not present'
+    );
+  }
+}, 'composite member is hidden from the result of ' +
+   'KeyframeEffect::getKeyframes()');
+
 done();
 </script>
 </body>

dom/animation/test/mozilla/file_disable_animations_api_get_animations.html

@@ -15,11 +15,6 @@ test(t => {
 }, 'Document.getAnimations() is not available when getAnimations pref is'
     + ' disabled');
 
-test(t => {
-  assert_false('CSSPseudoElement' in window);
-}, 'CSSPseudoElement interface is not available when getAnimations pref is'
-    + ' disabled');
-
 done();
 </script>
 </body>

dom/animation/test/mozilla/file_restyles.html

@@ -1131,6 +1131,19 @@ waitForAllPaints(() => {
     }
   );
 
+  add_task_if_omta_enabled(
+    async function animation_visibility_and_opacity() {
+      const div = addDiv(null);
+      const animation1 = div.animate({ opacity: [0, 1] }, 100 * MS_PER_SEC);
+      const animation2 = div.animate({ visibility: ['hidden', 'visible'] }, 100 * MS_PER_SEC);
+      await waitForAnimationReadyToRestyle(animation1);
+      await waitForAnimationReadyToRestyle(animation2);
+      const markers = await observeStyling(5);
+      is(markers.length, 5, 'The animation should not be throttled');
+      await ensureElementRemoval(div);
+    }
+  );
+
   add_task(async function restyling_for_animation_on_orphaned_element() {
     const div = addDiv(null);
     const animation = div.animate({ marginLeft: [ '0px', '100px' ] },
@@ -1956,6 +1969,90 @@ waitForAllPaints(() => {
 
     await ensureElementRemoval(div);
   });
+
+  add_task_if_omta_enabled(async function no_restyling_animations_in_opacity_zero_element() {
+    const div = addDiv(null, { style: 'animation: on-main-thread 100s infinite; opacity: 0' });
+    const animation = div.getAnimations()[0];
+
+    await waitForAnimationReadyToRestyle(animation);
+    const markers = await observeStyling(5);
+    is(markers.length, 0,
+       'Animations running on the main thread in opacity: 0 element ' +
+       'should never cause restyles');
+    await ensureElementRemoval(div);
+  });
+
+  add_task_if_omta_enabled(async function no_restyling_compositor_animations_in_opacity_zero_descendant() {
+    const container = addDiv(null, { style: 'opacity: 0' });
+    const child = addDiv(null, { style: 'animation: rotate 100s infinite;' });
+    container.appendChild(child);
+
+    const animation = child.getAnimations()[0];
+    await waitForAnimationReadyToRestyle(animation);
+    ok(!SpecialPowers.wrap(animation).isRunningOnCompositor);
+
+    const markers = await observeStyling(5);
+
+    is(markers.length, 0,
+       'Animations running on the compositor in opacity zero descendant element ' +
+       'should never cause restyles');
+    await ensureElementRemoval(container);
+  });
+
+  add_task_if_omta_enabled(async function no_restyling_compositor_animations_in_opacity_zero_descendant_abspos() {
+    const container = addDiv(null, { style: 'opacity: 0' });
+    const child = addDiv(null, { style: 'position: abspos; animation: rotate 100s infinite;' });
+    container.appendChild(child);
+
+    const animation = child.getAnimations()[0];
+    await waitForAnimationReadyToRestyle(animation);
+    ok(!SpecialPowers.wrap(animation).isRunningOnCompositor);
+
+    const markers = await observeStyling(5);
+
+    is(markers.length, 0,
+       'Animations running on the compositor in opacity zero abspos descendant element ' +
+       'should never cause restyles');
+    await ensureElementRemoval(container);
+  });
+
+  add_task_if_omta_enabled(async function restyling_main_thread_animations_in_opacity_zero_descendant_after_root_opacity_animation() {
+    const container = addDiv(null, { style: 'opacity: 0' });
+
+    const child = addDiv(null, { style: 'animation: on-main-thread 100s infinite;' });
+    container.appendChild(child);
+
+    // Animate the container from 1 to zero opacity and ensure the child animation is throttled then.
+    const containerAnimation = container.animate({ opacity: [ '1', '0' ] }, 100);
+    await containerAnimation.finished;
+
+    const animation = child.getAnimations()[0];
+    await waitForAnimationReadyToRestyle(animation);
+
+    const markers = await observeStyling(5);
+
+    is(markers.length, 0,
+       'Animations running on the compositor in opacity zero descendant element ' +
+       'should never cause restyles after root animation has finished');
+    await ensureElementRemoval(container);
+  });
+
+  add_task_if_omta_enabled(async function restyling_main_thread_animations_in_opacity_zero_descendant_during_root_opacity_animation() {
+    const container = addDiv(null, { style: 'opacity: 0; animation: opacity 100s infinite' });
+
+    const child = addDiv(null, { style: 'animation: on-main-thread 100s infinite;' });
+    container.appendChild(child);
+
+    const animation = child.getAnimations()[0];
+    await waitForAnimationReadyToRestyle(animation);
+
+    const markers = await observeStyling(5);
+
+    is(markers.length, 5,
+       'Animations in opacity zero descendant element ' +
+       'should not be throttled if root is animating opacity');
+    await ensureElementRemoval(container);
+  });
 });
 
 </script>

dom/animation/test/mozilla/test_cubic_bezier_limits.html

@@ -105,7 +105,7 @@ test(function(t) {
   div.style.transition = 'margin-left 100s cubic-bezier(0, 1e+39, 0, 0)';
   flushComputedStyle(div);
   div.style.marginLeft = '0px';
-  assert_equals(div.getAnimations()[0].effect.getKeyframes()[0].easing,
+  assert_equals(div.getAnimations()[0].effect.getTiming().easing,
     'cubic-bezier(0, ' + max_float + ', 0, 0)',
     'y1 control point for CSS transition on upper boundary');
   div.style.transition = '';
@@ -114,7 +114,7 @@ test(function(t) {
   div.style.transition = 'margin-left 100s cubic-bezier(0, 0, 0, 1e+39)';
   flushComputedStyle(div);
   div.style.marginLeft = '0px';
-  assert_equals(div.getAnimations()[0].effect.getKeyframes()[0].easing,
+  assert_equals(div.getAnimations()[0].effect.getTiming().easing,
     'cubic-bezier(0, 0, 0, ' + max_float + ')',
     'y2 control point for CSS transition on upper boundary');
   div.style.transition = '';
@@ -123,7 +123,7 @@ test(function(t) {
   div.style.transition = 'margin-left 100s cubic-bezier(0, -1e+39, 0, 0)';
   flushComputedStyle(div);
   div.style.marginLeft = '0px';
-  assert_equals(div.getAnimations()[0].effect.getKeyframes()[0].easing,
+  assert_equals(div.getAnimations()[0].effect.getTiming().easing,
     'cubic-bezier(0, ' + '-' + max_float + ', 0, 0)',
     'y1 control point for CSS transition on lower boundary');
   div.style.transition = '';
@@ -132,7 +132,7 @@ test(function(t) {
   div.style.transition = 'margin-left 100s cubic-bezier(0, 0, 0, -1e+39)';
   flushComputedStyle(div);
   div.style.marginLeft = '0px';
-  assert_equals(div.getAnimations()[0].effect.getKeyframes()[0].easing,
+  assert_equals(div.getAnimations()[0].effect.getTiming().easing,
     'cubic-bezier(0, 0, 0, ' + '-' + max_float + ')',
     'y2 control point for CSS transition on lower boundary');
 

dom/animation/test/mozilla/test_mainthread_synchronization_pref.html

@@ -0,0 +1,42 @@
+<!doctype html>
+<meta charset=utf-8>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="../testcommon.js"></script>
+<style>
+.compositable {
+  /* Element needs geometry to be eligible for layerization */
+  width: 100px;
+  height: 100px;
+  background-color: white;
+}
+</style>
+<body>
+<div id="log"></div>
+<script>
+'use strict';
+
+promise_test(async t => {
+  await SpecialPowers.pushPrefEnv({
+    set: [[ 'dom.animations.mainthread-synchronization-with-geometric-animations', false ]]
+  });
+
+  const elemA = addDiv(t, { class: 'compositable' });
+  const elemB = addDiv(t, { class: 'compositable' });
+
+  const animA = elemA.animate({ transform: [ 'translate(0px)',
+                                             'translate(100px)' ] },
+                              100 * MS_PER_SEC);
+  const animB = elemB.animate({ marginLeft: [ '0px', '100px' ] },
+                              100 * MS_PER_SEC);
+
+  await waitForPaints();
+
+  assert_true(SpecialPowers.wrap(animA).isRunningOnCompositor,
+      'Transform animation should not synchronize with margin-left animation ' +
+      'created within the same tick with disabling the corresponding pref');
+}, 'Transform animation should not synchronize with margin-left animation '
+   + 'created within the same tick with disabling the corresponding pref');
+
+</script>
+</body>

dom/audiochannel/AudioChannelService.cpp

@@ -719,11 +719,10 @@ void AudioChannelService::AudioChannelWindow::AppendAgent(
 
   RequestAudioFocus(aAgent);
   AppendAgentAndIncreaseAgentsNum(aAgent);
-  if (aAudible == AudibleState::eAudible) {
-    AudioAudibleChanged(aAgent, AudibleState::eAudible,
-                        AudibleChangedReasons::eDataAudibleChanged);
-  } else if (IsEnableAudioCompetingForAllAgents() &&
-             aAudible != AudibleState::eAudible) {
+  AudioAudibleChanged(aAgent, aAudible,
+                      AudibleChangedReasons::eDataAudibleChanged);
+  if (IsEnableAudioCompetingForAllAgents() &&
+      aAudible != AudibleState::eAudible) {
     NotifyAudioCompetingChanged(aAgent);
   }
 }

dom/audiochannel/AudioChannelService.h

@@ -49,6 +49,41 @@ class AudioChannelService final : public nsIObserver {
   NS_DECL_NSIOBSERVER
 
   /**
+   * We use `AudibleState` to represent the audible state of an owner of audio
+   * channel agent. Those information in AudioChannelWindow could help us to
+   * determine if a tab is being audible or not, in order to tell Chrome JS to
+   * show the sound indicator or delayed autoplay icon on the tab bar.
+   *
+   * - Sound indicator
+   * When a tab is playing sound, we would show the sound indicator on tab bar
+   * to tell users that this tab is producing sound now. In addition, the sound
+   * indicator also give users an ablility to mute or unmute tab.
+   *
+   * When an AudioChannelWindow first contains an agent with state `eAudible`,
+   * or an AudioChannelWindow losts its last agent with state `eAudible`, we
+   * would notify Chrome JS about those changes, to tell them that a tab has
+   * been being audible or not, in order to display or remove the indicator for
+   * a corresponding tab.
+   *
+   * - Delayed autoplay icon (Play Tab icon)
+   * When we enable delaying autoplay, which is to postpone the autoplay media
+   * for unvisited tab until it first goes to foreground, or user click the
+   * play tab icon to resume the delayed media.
+   *
+   * When an AudioChannelWindow first contains an agent with state `eAudible` or
+   * `eMaybeAudible`, we would notify Chrome JS about this change, in order to
+   * show the delayed autoplay tab icon to user, which is used to notice user
+   * there is a media being delayed starting, and then user can click the play
+   * tab icon to resume the start of media, or visit that tab to resume delayed
+   * media automatically.
+   *
+   * According to our UX design, we don't show this icon for inaudible media.
+   * The reason of showing the icon for a tab, where the agent starts with state
+   * `eMaybeAudible`, is because some video might be silent in the beginning
+   * but would soon become audible later.
+   *
+   * ---------------------------------------------------------------------------
+   *
    * eNotAudible : agent is not audible
    * eMaybeAudible : agent is not audible now, but it might be audible later
    * eAudible : agent is audible now

dom/base/AbstractRange.cpp

@@ -14,6 +14,7 @@
 #include "nsGkAtoms.h"
 #include "nsINode.h"
 #include "nsRange.h"
+#include "nsTArray.h"
 
 namespace mozilla {
 namespace dom {
@@ -42,6 +43,10 @@ template nsresult AbstractRange::SetStartAndEndInternal(
 template nsresult AbstractRange::SetStartAndEndInternal(
     const RawRangeBoundary& aStartBoundary,
     const RawRangeBoundary& aEndBoundary, StaticRange* aRange);
+template bool AbstractRange::MaybeCacheToReuse(nsRange& aInstance);
+template bool AbstractRange::MaybeCacheToReuse(StaticRange& aInstance);
+
+bool AbstractRange::sHasShutDown = false;
 
 NS_IMPL_CYCLE_COLLECTING_ADDREF(AbstractRange)
 NS_IMPL_CYCLE_COLLECTING_RELEASE(AbstractRange)
@@ -68,12 +73,56 @@ NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 
 NS_IMPL_CYCLE_COLLECTION_TRACE_WRAPPERCACHE(AbstractRange)
 
+// NOTE: If you need to change default value of members of AbstractRange,
+//       update nsRange::Create(nsINode* aNode) and ClearForReuse() too.
 AbstractRange::AbstractRange(nsINode* aNode)
     : mIsPositioned(false), mIsGenerated(false), mCalledByJS(false) {
+  Init(aNode);
+}
+
+void AbstractRange::Init(nsINode* aNode) {
   MOZ_ASSERT(aNode, "range isn't in a document!");
   mOwner = aNode->OwnerDoc();
 }
 
+// static
+void AbstractRange::Shutdown() {
+  sHasShutDown = true;
+  if (nsTArray<RefPtr<nsRange>>* cachedRanges = nsRange::sCachedRanges) {
+    nsRange::sCachedRanges = nullptr;
+    cachedRanges->Clear();
+    delete cachedRanges;
+  }
+  if (nsTArray<RefPtr<StaticRange>>* cachedRanges =
+          StaticRange::sCachedRanges) {
+    StaticRange::sCachedRanges = nullptr;
+    cachedRanges->Clear();
+    delete cachedRanges;
+  }
+}
+
+// static
+template <class RangeType>
+bool AbstractRange::MaybeCacheToReuse(RangeType& aInstance) {
+  static const size_t kMaxRangeCache = 64;
+
+  // If the instance is not used by JS and the cache is not yet full, we
+  // should reuse it.  Otherwise, delete it.
+  if (sHasShutDown || aInstance.GetWrapperMaybeDead() || aInstance.GetFlags() ||
+      (RangeType::sCachedRanges &&
+       RangeType::sCachedRanges->Length() == kMaxRangeCache)) {
+    return false;
+  }
+
+  aInstance.ClearForReuse();
+
+  if (!RangeType::sCachedRanges) {
+    RangeType::sCachedRanges = new nsTArray<RefPtr<RangeType>>(16);
+  }
+  RangeType::sCachedRanges->AppendElement(&aInstance);
+  return true;
+}
+
 nsINode* AbstractRange::GetClosestCommonInclusiveAncestor() const {
   return mIsPositioned ? nsContentUtils::GetClosestCommonInclusiveAncestor(
                              mStart.Container(), mEnd.Container())

dom/base/AbstractRange.h

@@ -23,6 +23,11 @@ class AbstractRange : public nsISupports, public nsWrapperCache {
   AbstractRange() = delete;
   explicit AbstractRange(const AbstractRange& aOther) = delete;
 
+  /**
+   * Called when the process is shutting down.
+   */
+  static void Shutdown();
+
   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
   NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(AbstractRange)
 
@@ -83,6 +88,22 @@ class AbstractRange : public nsISupports, public nsWrapperCache {
       const RangeBoundaryBase<SPT, SRT>& aStartBoundary,
       const RangeBoundaryBase<EPT, ERT>& aEndBoundary, RangeType* aRange);
 
+  template <class RangeType>
+  static bool MaybeCacheToReuse(RangeType& aInstance);
+
+  void Init(nsINode* aNode);
+
+ private:
+  void ClearForReuse() {
+    mOwner = nullptr;
+    mStart = RangeBoundary();
+    mEnd = RangeBoundary();
+    mIsPositioned = false;
+    mIsGenerated = false;
+    mCalledByJS = false;
+  }
+
+ protected:
   RefPtr<Document> mOwner;
   RangeBoundary mStart;
   RangeBoundary mEnd;
@@ -94,6 +115,8 @@ class AbstractRange : public nsISupports, public nsWrapperCache {
   bool mIsGenerated;
   // Used by nsRange, but this should have this for minimizing the size.
   bool mCalledByJS;
+
+  static bool sHasShutDown;
 };
 
 }  // namespace dom

dom/base/AncestorIterator.h

@@ -0,0 +1,68 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * Implementation of some generic iterators over ancestor nodes.
+ *
+ * Note that these keep raw pointers to the nodes they iterate from, and as
+ * such the DOM should not be mutated while they're in use. There are debug
+ * assertions (via nsMutationGuard) that check this in debug builds.
+ */
+
+#ifndef mozilla_dom_AncestorIterator_h
+#define mozilla_dom_AncestorIterator_h
+
+#include "nsINode.h"
+#include "nsIContentInlines.h"
+#include "FilteredNodeIterator.h"
+
+namespace mozilla {
+namespace dom {
+
+#ifdef DEBUG
+#  define MUTATION_GUARD(class_name_) \
+    nsMutationGuard mMutationGuard;   \
+    ~class_name_() { MOZ_ASSERT(!mMutationGuard.Mutated(0)); }
+#else
+#  define MUTATION_GUARD(class_name_)
+#endif
+
+#define DEFINE_ANCESTOR_ITERATOR(name_, method_)                         \
+  class Inclusive##name_ {                                               \
+    using Self = Inclusive##name_;                                       \
+                                                                         \
+   public:                                                               \
+    explicit Inclusive##name_(const nsINode& aNode)                      \
+        : mCurrent(const_cast<nsINode*>(&aNode)) {}                      \
+    Self& begin() { return *this; }                                      \
+    std::nullptr_t end() const { return nullptr; }                       \
+    bool operator!=(std::nullptr_t) const { return !!mCurrent; }         \
+    void operator++() { mCurrent = mCurrent->method_(); }                \
+    nsINode* operator*() { return mCurrent; }                            \
+                                                                         \
+    MUTATION_GUARD(Inclusive##name_)                                     \
+                                                                         \
+   protected:                                                            \
+    explicit Inclusive##name_(nsINode* aCurrent) : mCurrent(aCurrent) {} \
+    nsINode* mCurrent;                                                   \
+  };                                                                     \
+  class name_ : public Inclusive##name_ {                                \
+    using Super = Inclusive##name_;                                      \
+    explicit name_(const nsINode& aNode)                                 \
+        : Inclusive##name_(aNode.method_()) {}                           \
+  };                                                                     \
+  template <typename T>                                                  \
+  using name_##OfType = FilteredNodeIterator<T, name_>;                  \
+  template <typename T>                                                  \
+  using Inclusive##name_##OfType = FilteredNodeIterator<T, Inclusive##name_>;
+
+DEFINE_ANCESTOR_ITERATOR(Ancestors, GetParentNode)
+DEFINE_ANCESTOR_ITERATOR(FlatTreeAncestors, GetFlattenedTreeParentNode)
+
+#undef MUTATION_GUARD
+
+}  // namespace dom
+}  // namespace mozilla
+
+#endif  // mozilla_dom_AncestorIterator.h

dom/base/Attr.cpp

@@ -91,7 +91,12 @@ NS_INTERFACE_TABLE_HEAD(Attr)
 NS_INTERFACE_MAP_END
 
 NS_IMPL_CYCLE_COLLECTING_ADDREF(Attr)
-NS_IMPL_CYCLE_COLLECTING_RELEASE_WITH_LAST_RELEASE(Attr, LastRelease())
+
+NS_IMPL_CYCLE_COLLECTING_RELEASE_WITH_LAST_RELEASE_AND_DESTROY(Attr,
+                                                               LastRelease(),
+                                                               Destroy())
+
+NS_IMPL_DOMARENA_DESTROY(Attr)
 
 void Attr::SetMap(nsDOMAttributeMap* aMap) {
   if (mAttrMap && !aMap && sInitialized) {
@@ -116,7 +121,7 @@ nsresult Attr::SetOwnerDocument(Document* aDocument) {
 
   Document* doc = OwnerDoc();
   NS_ASSERTION(doc != aDocument, "bad call to Attr::SetOwnerDocument");
-  doc->DeleteAllPropertiesFor(this);
+  doc->RemoveAllPropertiesFor(this);
 
   RefPtr<dom::NodeInfo> newNodeInfo = aDocument->NodeInfoManager()->GetNodeInfo(
       mNodeInfo->NameAtom(), mNodeInfo->GetPrefixAtom(),
@@ -171,8 +176,9 @@ void Attr::SetNodeValueInternal(const nsAString& aNodeValue,
 nsresult Attr::Clone(dom::NodeInfo* aNodeInfo, nsINode** aResult) const {
   nsAutoString value;
   const_cast<Attr*>(this)->GetValue(value);
+  *aResult = new (aNodeInfo->NodeInfoManager())
+      Attr(nullptr, do_AddRef(aNodeInfo), value);
 
-  *aResult = new Attr(nullptr, do_AddRef(aNodeInfo), value);
   NS_ADDREF(*aResult);
 
   return NS_OK;

dom/base/Attr.h

@@ -26,13 +26,15 @@ class Document;
 // Attribute helper class used to wrap up an attribute with a dom
 // object that implements the DOM Attr interface.
 class Attr final : public nsINode {
-  virtual ~Attr() {}
+  virtual ~Attr() = default;
 
  public:
   Attr(nsDOMAttributeMap* aAttrMap, already_AddRefed<dom::NodeInfo>&& aNodeInfo,
        const nsAString& aValue);
 
-  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS_FINAL_DELETECYCLECOLLECTABLE
+
+  NS_DECL_DOMARENA_DESTROY
 
   NS_IMPL_FROMNODE_HELPER(Attr, IsAttr())
 

dom/base/AttrArray.cpp

@@ -310,6 +310,7 @@ nsresult AttrArray::DoSetMappedAttrStyleSheet(nsHTMLStyleSheet* aSheet) {
   RefPtr<nsMappedAttributes> mapped =
       GetModifiableMapped(nullptr, nullptr, false);
 
+  mapped->DropStyleSheetReference();
   mapped->SetStyleSheet(aSheet);
 
   return MakeMappedUnique(mapped);

dom/base/BarProps.cpp

@@ -5,8 +5,8 @@
 #include "mozilla/dom/BarProps.h"
 #include "mozilla/dom/BarPropBinding.h"
 #include "nsContentUtils.h"
+#include "nsDocShell.h"
 #include "nsGlobalWindow.h"
-#include "nsIScrollable.h"
 #include "nsIWebBrowserChrome.h"
 
 namespace mozilla {
@@ -17,7 +17,7 @@ namespace dom {
 //
 BarProp::BarProp(nsGlobalWindowInner* aWindow) : mDOMWindow(aWindow) {}
 
-BarProp::~BarProp() {}
+BarProp::~BarProp() = default;
 
 nsPIDOMWindowInner* BarProp::GetParentObject() const { return mDOMWindow; }
 
@@ -88,7 +88,7 @@ already_AddRefed<nsIWebBrowserChrome> BarProp::GetBrowserChrome() {
 
 MenubarProp::MenubarProp(nsGlobalWindowInner* aWindow) : BarProp(aWindow) {}
 
-MenubarProp::~MenubarProp() {}
+MenubarProp::~MenubarProp() = default;
 
 bool MenubarProp::GetVisible(CallerType aCallerType, ErrorResult& aRv) {
   return BarProp::GetVisibleByFlag(nsIWebBrowserChrome::CHROME_MENUBAR, aRv);
@@ -106,7 +106,7 @@ void MenubarProp::SetVisible(bool aVisible, CallerType aCallerType,
 
 ToolbarProp::ToolbarProp(nsGlobalWindowInner* aWindow) : BarProp(aWindow) {}
 
-ToolbarProp::~ToolbarProp() {}
+ToolbarProp::~ToolbarProp() = default;
 
 bool ToolbarProp::GetVisible(CallerType aCallerType, ErrorResult& aRv) {
   return BarProp::GetVisibleByFlag(nsIWebBrowserChrome::CHROME_TOOLBAR, aRv);
@@ -125,7 +125,7 @@ void ToolbarProp::SetVisible(bool aVisible, CallerType aCallerType,
 LocationbarProp::LocationbarProp(nsGlobalWindowInner* aWindow)
     : BarProp(aWindow) {}
 
-LocationbarProp::~LocationbarProp() {}
+LocationbarProp::~LocationbarProp() = default;
 
 bool LocationbarProp::GetVisible(CallerType aCallerType, ErrorResult& aRv) {
   return BarProp::GetVisibleByFlag(nsIWebBrowserChrome::CHROME_LOCATIONBAR,
@@ -145,7 +145,7 @@ void LocationbarProp::SetVisible(bool aVisible, CallerType aCallerType,
 PersonalbarProp::PersonalbarProp(nsGlobalWindowInner* aWindow)
     : BarProp(aWindow) {}
 
-PersonalbarProp::~PersonalbarProp() {}
+PersonalbarProp::~PersonalbarProp() = default;
 
 bool PersonalbarProp::GetVisible(CallerType aCallerType, ErrorResult& aRv) {
   return BarProp::GetVisibleByFlag(nsIWebBrowserChrome::CHROME_PERSONAL_TOOLBAR,
@@ -164,7 +164,7 @@ void PersonalbarProp::SetVisible(bool aVisible, CallerType aCallerType,
 
 StatusbarProp::StatusbarProp(nsGlobalWindowInner* aWindow) : BarProp(aWindow) {}
 
-StatusbarProp::~StatusbarProp() {}
+StatusbarProp::~StatusbarProp() = default;
 
 bool StatusbarProp::GetVisible(CallerType aCallerType, ErrorResult& aRv) {
   return BarProp::GetVisibleByFlag(nsIWebBrowserChrome::CHROME_STATUSBAR, aRv);
@@ -183,60 +183,24 @@ void StatusbarProp::SetVisible(bool aVisible, CallerType aCallerType,
 ScrollbarsProp::ScrollbarsProp(nsGlobalWindowInner* aWindow)
     : BarProp(aWindow) {}
 
-ScrollbarsProp::~ScrollbarsProp() {}
+ScrollbarsProp::~ScrollbarsProp() = default;
 
 bool ScrollbarsProp::GetVisible(CallerType aCallerType, ErrorResult& aRv) {
   if (!mDOMWindow) {
     return true;
   }
 
-  nsCOMPtr<nsIScrollable> scroller =
-      do_QueryInterface(mDOMWindow->GetDocShell());
-
-  if (!scroller) {
+  nsIDocShell* ds = mDOMWindow->GetDocShell();
+  if (!ds) {
     return true;
   }
 
-  int32_t prefValue;
-  scroller->GetDefaultScrollbarPreferences(nsIScrollable::ScrollOrientation_Y,
-                                           &prefValue);
-  if (prefValue != nsIScrollable::Scrollbar_Never) {
-    return true;
-  }
-
-  scroller->GetDefaultScrollbarPreferences(nsIScrollable::ScrollOrientation_X,
-                                           &prefValue);
-  return prefValue != nsIScrollable::Scrollbar_Never;
+  ScrollbarPreference pref = nsDocShell::Cast(ds)->ScrollbarPreference();
+  return pref != ScrollbarPreference::Never;
 }
 
-void ScrollbarsProp::SetVisible(bool aVisible, CallerType aCallerType,
-                                ErrorResult& aRv) {
-  if (aCallerType != CallerType::System) {
-    return;
-  }
-
-  /* Scrollbars, unlike the other barprops, implement visibility directly
-     rather than handing off to the superclass (and from there to the
-     chrome window) because scrollbar visibility uniquely applies only
-     to the window making the change (arguably. it does now, anyway.)
-     and because embedding apps have no interface for implementing this
-     themselves, and therefore the implementation must be internal. */
-
-  nsContentUtils::SetScrollbarsVisibility(mDOMWindow->GetDocShell(), aVisible);
-
-  /* Notably absent is the part where we notify the chrome window using
-     GetBrowserChrome()->SetChromeFlags(). Given the possibility of multiple
-     DOM windows (multiple top-level windows, even) within a single
-     chrome window, the historical concept of a single "has scrollbars"
-     flag in the chrome is inapplicable, and we can't tell at this level
-     whether we represent the particular DOM window that makes this decision
-     for the chrome.
-
-     So only this object (and its corresponding DOM window) knows whether
-     scrollbars are visible. The corresponding chrome window will need to
-     ask (one of) its DOM window(s) when it needs to know about scrollbar
-     visibility, rather than caching its own copy of that information.
-  */
+void ScrollbarsProp::SetVisible(bool aVisible, CallerType, ErrorResult&) {
+  /* Do nothing */
 }
 
 }  // namespace dom

dom/base/BarProps.h

@@ -36,8 +36,7 @@ class BarProp : public nsISupports, public nsWrapperCache {
 
   nsPIDOMWindowInner* GetParentObject() const;
 
-  virtual JSObject* WrapObject(JSContext* aCx,
-                               JS::Handle<JSObject*> aGivenProto) override;
+  JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) final;
 
   virtual bool GetVisible(CallerType aCallerType, ErrorResult& aRv) = 0;
   virtual void SetVisible(bool aVisible, CallerType aCallerType,
@@ -61,9 +60,9 @@ class MenubarProp final : public BarProp {
   explicit MenubarProp(nsGlobalWindowInner* aWindow);
   virtual ~MenubarProp();
 
-  virtual bool GetVisible(CallerType aCallerType, ErrorResult& aRv) override;
-  virtual void SetVisible(bool aVisible, CallerType aCallerType,
-                          ErrorResult& aRv) override;
+  bool GetVisible(CallerType aCallerType, ErrorResult& aRv) override;
+  void SetVisible(bool aVisible, CallerType aCallerType,
+                  ErrorResult& aRv) override;
 };
 
 // Script "toolbar" object
@@ -72,9 +71,9 @@ class ToolbarProp final : public BarProp {
   explicit ToolbarProp(nsGlobalWindowInner* aWindow);
   virtual ~ToolbarProp();
 
-  virtual bool GetVisible(CallerType aCallerType, ErrorResult& aRv) override;
-  virtual void SetVisible(bool aVisible, CallerType aCallerType,
-                          ErrorResult& aRv) override;
+  bool GetVisible(CallerType aCallerType, ErrorResult& aRv) override;
+  void SetVisible(bool aVisible, CallerType aCallerType,
+                  ErrorResult& aRv) override;
 };
 
 // Script "locationbar" object
@@ -83,9 +82,9 @@ class LocationbarProp final : public BarProp {
   explicit LocationbarProp(nsGlobalWindowInner* aWindow);
   virtual ~LocationbarProp();
 
-  virtual bool GetVisible(CallerType aCallerType, ErrorResult& aRv) override;
-  virtual void SetVisible(bool aVisible, CallerType aCallerType,
-                          ErrorResult& aRv) override;
+  bool GetVisible(CallerType aCallerType, ErrorResult& aRv) override;
+  void SetVisible(bool aVisible, CallerType aCallerType,
+                  ErrorResult& aRv) override;
 };
 
 // Script "personalbar" object
@@ -94,9 +93,9 @@ class PersonalbarProp final : public BarProp {
   explicit PersonalbarProp(nsGlobalWindowInner* aWindow);
   virtual ~PersonalbarProp();
 
-  virtual bool GetVisible(CallerType aCallerType, ErrorResult& aRv) override;
-  virtual void SetVisible(bool aVisible, CallerType aCallerType,
-                          ErrorResult& aRv) override;
+  bool GetVisible(CallerType aCallerType, ErrorResult& aRv) override;
+  void SetVisible(bool aVisible, CallerType aCallerType,
+                  ErrorResult& aRv) override;
 };
 
 // Script "statusbar" object
@@ -105,9 +104,9 @@ class StatusbarProp final : public BarProp {
   explicit StatusbarProp(nsGlobalWindowInner* aWindow);
   virtual ~StatusbarProp();
 
-  virtual bool GetVisible(CallerType aCallerType, ErrorResult& aRv) override;
-  virtual void SetVisible(bool aVisible, CallerType aCallerType,
-                          ErrorResult& aRv) override;
+  bool GetVisible(CallerType aCallerType, ErrorResult& aRv) override;
+  void SetVisible(bool aVisible, CallerType aCallerType,
+                  ErrorResult& aRv) override;
 };
 
 // Script "scrollbars" object
@@ -116,9 +115,9 @@ class ScrollbarsProp final : public BarProp {
   explicit ScrollbarsProp(nsGlobalWindowInner* aWindow);
   virtual ~ScrollbarsProp();
 
-  virtual bool GetVisible(CallerType aCallerType, ErrorResult& aRv) override;
-  virtual void SetVisible(bool aVisible, CallerType aCallerType,
-                          ErrorResult& aRv) override;
+  bool GetVisible(CallerType aCallerType, ErrorResult& aRv) override;
+  void SetVisible(bool aVisible, CallerType aCallerType,
+                  ErrorResult& aRv) override;
 };
 
 }  // namespace dom

dom/base/BindContext.h

@@ -59,10 +59,7 @@ struct MOZ_STACK_CLASS BindContext final {
                            : nullptr),
         mInComposedDoc(aParent.IsInComposedDoc()),
         mInUncomposedDoc(aParent.IsInUncomposedDoc()),
-        mSubtreeRootChanges(true),
-        mCollectingDisplayedNodeDataDuringLoad(
-            ShouldCollectDisplayedNodeDataDuringLoad(mInComposedDoc, mDoc,
-                                                     aParent)) {}
+        mSubtreeRootChanges(true) {}
 
   // When re-binding a shadow host into a tree, we re-bind all the shadow tree
   // from the root. In that case, the shadow tree contents remain within the
@@ -75,10 +72,7 @@ struct MOZ_STACK_CLASS BindContext final {
         mBindingParent(aShadowRoot.Host()),
         mInComposedDoc(aShadowRoot.IsInComposedDoc()),
         mInUncomposedDoc(false),
-        mSubtreeRootChanges(false),
-        mCollectingDisplayedNodeDataDuringLoad(
-            ShouldCollectDisplayedNodeDataDuringLoad(mInComposedDoc, mDoc,
-                                                     aShadowRoot)) {}
+        mSubtreeRootChanges(false) {}
 
   // This constructor is meant to be used when inserting native-anonymous
   // children into a subtree.
@@ -88,10 +82,7 @@ struct MOZ_STACK_CLASS BindContext final {
         mBindingParent(&aParentElement),
         mInComposedDoc(aParentElement.IsInComposedDoc()),
         mInUncomposedDoc(aParentElement.IsInUncomposedDoc()),
-        mSubtreeRootChanges(true),
-        mCollectingDisplayedNodeDataDuringLoad(
-            ShouldCollectDisplayedNodeDataDuringLoad(mInComposedDoc, mDoc,
-                                                     aParentElement)) {
+        mSubtreeRootChanges(true) {
     MOZ_ASSERT(mInComposedDoc, "Binding NAC in a disconnected subtree?");
   }
 
@@ -101,27 +92,13 @@ struct MOZ_STACK_CLASS BindContext final {
         mBindingParent(aBinding.GetBoundElement()),
         mInComposedDoc(aParentElement.IsInComposedDoc()),
         mInUncomposedDoc(aParentElement.IsInUncomposedDoc()),
-        mSubtreeRootChanges(true),
-        mCollectingDisplayedNodeDataDuringLoad(
-            ShouldCollectDisplayedNodeDataDuringLoad(mInComposedDoc, mDoc,
-                                                     aParentElement)) {}
-
-  bool CollectingDisplayedNodeDataDuringLoad() const {
-    return mCollectingDisplayedNodeDataDuringLoad;
-  }
+        mSubtreeRootChanges(true) {}
 
  private:
   static bool IsLikelyUndisplayed(const nsINode& aParent) {
     return aParent.IsAnyOfHTMLElements(nsGkAtoms::style, nsGkAtoms::script);
   }
 
-  static bool ShouldCollectDisplayedNodeDataDuringLoad(bool aConnected,
-                                                       Document& aDoc,
-                                                       nsINode& aParent) {
-    return aDoc.GetReadyStateEnum() == Document::READYSTATE_LOADING &&
-           aConnected && !IsLikelyUndisplayed(aParent);
-  }
-
   Document& mDoc;
 
   Element* const mBindingParent;
@@ -132,27 +109,6 @@ struct MOZ_STACK_CLASS BindContext final {
   // Whether the bind operation will change the subtree root of the content
   // we're binding.
   const bool mSubtreeRootChanges;
-
-  // Whether it's likely that we're in an undisplayed part of the DOM.
-  //
-  // NOTE(emilio): We don't inherit this in BindContext's for Shadow DOM or XBL
-  // or such. This means that if you have a shadow tree inside an undisplayed
-  // element it will be incorrectly counted.  But given our current definition
-  // of undisplayed element this is not likely to matter in practice.
-  bool mCollectingDisplayedNodeDataDuringLoad;
-};
-
-struct MOZ_STACK_CLASS BindContext::NestingLevel {
-  explicit NestingLevel(BindContext& aContext, const Element& aParent)
-      : mRestoreCollecting(aContext.mCollectingDisplayedNodeDataDuringLoad) {
-    if (aContext.mCollectingDisplayedNodeDataDuringLoad) {
-      aContext.mCollectingDisplayedNodeDataDuringLoad =
-          BindContext::IsLikelyUndisplayed(aParent);
-    }
-  }
-
- private:
-  AutoRestore<bool> mRestoreCollecting;
 };
 
 }  // namespace dom

dom/base/BodyConsumer.cpp

@@ -735,7 +735,7 @@ void BodyConsumer::ContinueConsumeBody(nsresult aStatus, uint32_t aResultLength,
 
   error.WouldReportJSException();
   if (error.Failed()) {
-    localPromise->MaybeReject(error);
+    localPromise->MaybeReject(std::move(error));
   }
 }
 

dom/base/BodyStream.cpp

@@ -318,7 +318,7 @@ BodyStream::BodyStream(nsIGlobalObject* aGlobal,
   MOZ_DIAGNOSTIC_ASSERT(aStreamHolder);
 }
 
-BodyStream::~BodyStream() {}
+BodyStream::~BodyStream() = default;
 
 void BodyStream::ErrorPropagation(JSContext* aCx,
                                   const MutexAutoLock& aProofOfLock,
@@ -337,10 +337,16 @@ void BodyStream::ErrorPropagation(JSContext* aCx,
   }
 
   // Let's use a generic error.
-  RefPtr<DOMException> error = DOMException::Create(NS_ERROR_DOM_TYPE_ERR);
+  ErrorResult rv;
+  // XXXbz can we come up with a better error message here to tell the
+  // consumer what went wrong?
+  rv.ThrowTypeError("Error in body stream");
 
   JS::Rooted<JS::Value> errorValue(aCx);
-  if (ToJSValue(aCx, error, &errorValue)) {
+  bool ok = ToJSValue(aCx, std::move(rv), &errorValue);
+  MOZ_RELEASE_ASSERT(ok, "ToJSValue never fails for ErrorResult");
+
+  {
     MutexAutoUnlock unlock(mMutex);
     JS::ReadableStreamError(aCx, aStream, errorValue);
   }

dom/base/CharacterData.cpp

@@ -458,13 +458,8 @@ nsresult CharacterData::BindToTree(BindContext& aContext, nsINode& aParent) {
           aParent.AsContent()->GetContainingShadow();
     }
 
-    if (IsInComposedDoc()) {
-      if (mText.IsBidi()) {
-        aContext.OwnerDoc().SetBidiEnabled();
-      }
-      if (aContext.CollectingDisplayedNodeDataDuringLoad()) {
-        aContext.OwnerDoc().AddToVisibleContentHeuristic(mText.GetLength());
-      }
+    if (IsInComposedDoc() && mText.IsBidi()) {
+      aContext.OwnerDoc().SetBidiEnabled();
     }
 
     // Clear the lazy frame construction bits.

dom/base/ChildIterator.h

@@ -310,7 +310,7 @@ class MOZ_NEEDS_MEMMOVABLE_MEMBERS StyleChildrenIterator
     return *this;
   }
 
-  ~StyleChildrenIterator() { MOZ_COUNT_DTOR(StyleChildrenIterator); }
+  MOZ_COUNTED_DTOR(StyleChildrenIterator)
 
   using AllChildrenIterator::GetNextChild;
   using AllChildrenIterator::GetPreviousChild;

dom/base/ChromeNodeList.cpp

@@ -25,7 +25,7 @@ void ChromeNodeList::Append(nsINode& aNode, ErrorResult& aError) {
   if (!aNode.IsContent()) {
     // nsINodeList deals with nsIContent objects only, so need to
     // filter out other nodes for now.
-    aError.Throw(NS_ERROR_DOM_TYPE_ERR);
+    aError.ThrowTypeError("The node passed in is not a ChildNode");
     return;
   }
 
@@ -34,7 +34,7 @@ void ChromeNodeList::Append(nsINode& aNode, ErrorResult& aError) {
 
 void ChromeNodeList::Remove(nsINode& aNode, ErrorResult& aError) {
   if (!aNode.IsContent()) {
-    aError.Throw(NS_ERROR_DOM_TYPE_ERR);
+    aError.ThrowTypeError("The node passed in is not a ChildNode");
     return;
   }
 

dom/base/ChromeUtils.cpp

@@ -83,12 +83,12 @@ void ChromeUtils::Base64URLEncode(GlobalObject& aGlobal,
   uint8_t* data = nullptr;
   if (aSource.IsArrayBuffer()) {
     const ArrayBuffer& buffer = aSource.GetAsArrayBuffer();
-    buffer.ComputeLengthAndData();
+    buffer.ComputeState();
     length = buffer.Length();
     data = buffer.Data();
   } else if (aSource.IsArrayBufferView()) {
     const ArrayBufferView& view = aSource.GetAsArrayBufferView();
-    view.ComputeLengthAndData();
+    view.ComputeState();
     length = view.Length();
     data = view.Data();
   } else {
@@ -774,7 +774,7 @@ already_AddRefed<Promise> ChromeUtils::RequestProcInfo(GlobalObject& aGlobal,
                     thread->mCpuKernel = entry.cpuKernel;
                     thread->mTid = entry.tid;
                   }
-                  procInfo.mThreads = threads;
+                  procInfo.mThreads = std::move(threads);
 
                   mozilla::dom::Sequence<mozilla::dom::ChildProcInfoDictionary>
                       children;
@@ -810,9 +810,9 @@ already_AddRefed<Promise> ChromeUtils::RequestProcInfo(GlobalObject& aGlobal,
                       thread->mTid = entry.tid;
                       thread->mName.Assign(entry.name);
                     }
-                    childProcInfo->mThreads = threads;
+                    childProcInfo->mThreads = std::move(threads);
                   }
-                  procInfo.mChildren = children;
+                  procInfo.mChildren = std::move(children);
                   domPromise->MaybeResolve(procInfo);
                 };  // end of ProcInfoResolver
 

dom/base/Comment.cpp

@@ -17,12 +17,13 @@ using namespace dom;
 namespace mozilla {
 namespace dom {
 
-Comment::~Comment() {}
+Comment::~Comment() = default;
 
 already_AddRefed<CharacterData> Comment::CloneDataNode(
     mozilla::dom::NodeInfo* aNodeInfo, bool aCloneText) const {
   RefPtr<mozilla::dom::NodeInfo> ni = aNodeInfo;
-  RefPtr<Comment> it = new Comment(ni.forget());
+  auto* nim = ni->NodeInfoManager();
+  RefPtr<Comment> it = new (nim) Comment(ni.forget());
   if (aCloneText) {
     it->mText = mText;
   }

dom/base/Crypto.cpp

@@ -29,7 +29,7 @@ NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(Crypto, mParent, mSubtle)
 
 Crypto::Crypto(nsIGlobalObject* aParent) : mParent(aParent) {}
 
-Crypto::~Crypto() {}
+Crypto::~Crypto() = default;
 
 /* virtual */
 JSObject* Crypto::WrapObject(JSContext* aCx,
@@ -58,7 +58,7 @@ void Crypto::GetRandomValues(JSContext* aCx, const ArrayBufferView& aArray,
       return;
   }
 
-  aArray.ComputeLengthAndData();
+  aArray.ComputeState();
   uint32_t dataLen = aArray.Length();
   if (dataLen == 0) {
     NS_WARNING("ArrayBufferView length is 0, cannot continue");

dom/base/CustomElementRegistry.cpp

@@ -656,8 +656,7 @@ bool CustomElementRegistry::JSObjectToAtomArray(
 
   if (!iterable.isUndefined()) {
     if (!iterable.isObject()) {
-      aRv.ThrowTypeError<MSG_NOT_SEQUENCE>(
-          NS_LITERAL_STRING("CustomElementRegistry.define: ") + aName);
+      aRv.ThrowTypeError<MSG_NOT_SEQUENCE>(NS_ConvertUTF16toUTF8(aName));
       return false;
     }
 
@@ -668,8 +667,7 @@ bool CustomElementRegistry::JSObjectToAtomArray(
     }
 
     if (!iter.valueIsIterable()) {
-      aRv.ThrowTypeError<MSG_NOT_SEQUENCE>(
-          NS_LITERAL_STRING("CustomElementRegistry.define: ") + aName);
+      aRv.ThrowTypeError<MSG_NOT_SEQUENCE>(NS_ConvertUTF16toUTF8(aName));
       return false;
     }
 
@@ -691,10 +689,9 @@ bool CustomElementRegistry::JSObjectToAtomArray(
         return false;
       }
 
-      if (!aArray.AppendElement(NS_Atomize(attrStr))) {
-        aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
-        return false;
-      }
+      // XXX(Bug 1631371) Check if this should use a fallible operation as it
+      // pretended earlier.
+      aArray.AppendElement(NS_Atomize(attrStr));
     }
   }
 
@@ -728,8 +725,7 @@ void CustomElementRegistry::Define(
    *    these steps.
    */
   if (!JS::IsConstructor(constructorUnwrapped)) {
-    aRv.ThrowTypeError<MSG_NOT_CONSTRUCTOR>(
-        NS_LITERAL_STRING("Argument 2 of CustomElementRegistry.define"));
+    aRv.ThrowTypeError<MSG_NOT_CONSTRUCTOR>("Argument 2");
     return;
   }
 
@@ -868,8 +864,7 @@ void CustomElementRegistry::Define(
      * 14.2. If Type(prototype) is not Object, then throw a TypeError exception.
      */
     if (!prototype.isObject()) {
-      aRv.ThrowTypeError<MSG_NOT_OBJECT>(NS_LITERAL_STRING(
-          "CustomElementRegistry.define: constructor.prototype"));
+      aRv.ThrowTypeError<MSG_NOT_OBJECT>("constructor.prototype");
       return;
     }
 
@@ -961,7 +956,7 @@ void CustomElementRegistry::Define(
       disableInternals, disableShadow);
 
   CustomElementDefinition* def = definition.get();
-  mCustomDefinitions.Put(nameAtom, definition.forget());
+  mCustomDefinitions.Put(nameAtom, std::move(definition));
 
   MOZ_ASSERT(mCustomDefinitions.Count() == mConstructors.count(),
              "Number of entries should be the same");
@@ -1020,7 +1015,7 @@ void CustomElementRegistry::SetElementCreationCallback(
   }
 
   RefPtr<CustomElementCreationCallback> callback = &aCallback;
-  mElementCreationCallbacks.Put(nameAtom, callback.forget());
+  mElementCreationCallbacks.Put(nameAtom, std::move(callback));
 }
 
 void CustomElementRegistry::Upgrade(nsINode& aRoot) {
@@ -1119,7 +1114,7 @@ static void DoUpgrade(Element* aElement, CustomElementDefinition* aDefinition,
   // always forms the return value from a JSObject.
   if (NS_FAILED(UNWRAP_OBJECT(Element, &constructResult, element)) ||
       element != aElement) {
-    aRv.ThrowTypeError(u"Custom element constructor returned a wrong element");
+    aRv.ThrowTypeError("Custom element constructor returned a wrong element");
     return;
   }
 }

dom/base/CustomElementRegistry.h

@@ -117,7 +117,7 @@ struct CustomElementData {
   }
 
  private:
-  virtual ~CustomElementData() {}
+  virtual ~CustomElementData() = default;
 
   // Custom element type, for <button is="x-button"> or <x-button>
   // this would be x-button.
@@ -193,7 +193,7 @@ struct CustomElementDefinition {
   }
 
  private:
-  ~CustomElementDefinition() {}
+  ~CustomElementDefinition() = default;
 };
 
 class CustomElementReaction {
@@ -290,7 +290,8 @@ class CustomElementReactionsStack {
   }
 
  private:
-  ~CustomElementReactionsStack(){};
+  ~CustomElementReactionsStack() = default;
+  ;
 
   /**
    * Push a new element queue onto the custom element reactions stack.

dom/base/DOMArena.h

@@ -0,0 +1,52 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+#ifndef DOM_Arena_h___
+#define DOM_Arena_h___
+#include "nsISupportsImpl.h"
+#include "mozmemory.h"
+
+#define NS_DECL_DOMARENA_DESTROY void Destroy(void);
+
+#define NS_IMPL_DOMARENA_DESTROY(class)                              \
+  void class ::Destroy(void) {                                       \
+    if (StaticPrefs::dom_arena_allocator_enabled_AtStartup()) {      \
+      RefPtr<nsNodeInfoManager> nim = OwnerDoc()->NodeInfoManager(); \
+      RefPtr<DOMArena> arena =                                       \
+          HasFlag(NODE_KEEPS_DOMARENA)                               \
+              ? nsContentUtils::TakeEntryFromDOMArenaTable(this)     \
+              : nullptr;                                             \
+      this->~class();                                                \
+      MOZ_ASSERT(nim, "nsNodeInfoManager needs to be initialized");  \
+      nim->Free(this);                                               \
+    } else {                                                         \
+      delete this;                                                   \
+    }                                                                \
+  }
+
+namespace mozilla {
+namespace dom {
+
+class DOMArena {
+ public:
+  friend class DocGroup;
+  DOMArena() { mArenaId = moz_create_arena(); }
+
+  NS_INLINE_DECL_REFCOUNTING(DOMArena)
+
+  void* Allocate(size_t aSize) {
+    void* ret = moz_arena_malloc(mArenaId, aSize);
+    if (!ret) {
+      MOZ_CRASH("run out of memory");
+    }
+    return ret;
+  }
+
+ private:
+  ~DOMArena() { moz_dispose_arena(mArenaId); }
+  arena_id_t mArenaId;
+};
+}  // namespace dom
+}  // namespace mozilla
+#endif

dom/base/DOMException.h

@@ -168,7 +168,7 @@ class DOMException : public Exception {
                                                const nsACString& aMessage);
 
  protected:
-  virtual ~DOMException() {}
+  virtual ~DOMException() = default;
 
   uint16_t mCode;
 };

dom/base/DOMImplementation.cpp

@@ -158,7 +158,8 @@ nsresult DOMImplementation::CreateHTMLDocument(const nsAString& aTitle,
     rv = head->AppendChildTo(title, false);
     NS_ENSURE_SUCCESS(rv, rv);
 
-    RefPtr<nsTextNode> titleText = new nsTextNode(doc->NodeInfoManager());
+    RefPtr<nsTextNode> titleText =
+        new (doc->NodeInfoManager()) nsTextNode(doc->NodeInfoManager());
     rv = titleText->SetText(aTitle, false);
     NS_ENSURE_SUCCESS(rv, rv);
     rv = title->AppendChildTo(titleText, false);

dom/base/DOMImplementation.h

@@ -23,7 +23,7 @@ class Document;
 class DocumentType;
 
 class DOMImplementation final : public nsISupports, public nsWrapperCache {
-  ~DOMImplementation() {}
+  ~DOMImplementation() = default;
 
  public:
   DOMImplementation(Document* aOwner, nsIGlobalObject* aScriptObject,

dom/base/DOMIntersectionObserver.cpp

@@ -90,7 +90,7 @@ already_AddRefed<DOMIntersectionObserver> DOMIntersectionObserver::Constructor(
     observer->mThresholds.SetCapacity(thresholds.Length());
     for (const auto& thresh : thresholds) {
       if (thresh < 0.0 || thresh > 1.0) {
-        aRv.ThrowTypeError<dom::MSG_THRESHOLD_RANGE_ERROR>();
+        aRv.ThrowRangeError<dom::MSG_THRESHOLD_RANGE_ERROR>();
         return nullptr;
       }
       observer->mThresholds.AppendElement(thresh);
@@ -99,7 +99,7 @@ already_AddRefed<DOMIntersectionObserver> DOMIntersectionObserver::Constructor(
   } else {
     double thresh = aOptions.mThreshold.GetAsDouble();
     if (thresh < 0.0 || thresh > 1.0) {
-      aRv.ThrowTypeError<dom::MSG_THRESHOLD_RANGE_ERROR>();
+      aRv.ThrowRangeError<dom::MSG_THRESHOLD_RANGE_ERROR>();
       return nullptr;
     }
     observer->mThresholds.AppendElement(thresh);

dom/base/DOMIntersectionObserver.h

@@ -17,7 +17,7 @@ class DOMIntersectionObserver;
 
 class DOMIntersectionObserverEntry final : public nsISupports,
                                            public nsWrapperCache {
-  ~DOMIntersectionObserverEntry() {}
+  ~DOMIntersectionObserverEntry() = default;
 
  public:
   DOMIntersectionObserverEntry(nsISupports* aOwner, DOMHighResTimeStamp aTime,

dom/base/DOMMatrix.cpp

@@ -58,8 +58,7 @@ static bool ValidateAndFixupMatrix2DInit(DOMMatrix2DInit& aMatrixInit,
     }                                                     \
   }
 #define ValidateAndSet(field, alias, fieldName, aliasName, defaultValue) \
-  ValidateAliases((field), (alias), NS_LITERAL_STRING(fieldName),        \
-                  NS_LITERAL_STRING(aliasName));                         \
+  ValidateAliases((field), (alias), fieldName, aliasName);               \
   SetFromAliasOrDefault((field), (alias), (defaultValue));
 
   ValidateAndSet(aMatrixInit.mM11, aMatrixInit.mA, "m11", "a", 1);
@@ -79,17 +78,16 @@ static bool ValidateAndFixupMatrix2DInit(DOMMatrix2DInit& aMatrixInit,
 // https://drafts.fxtf.org/geometry/#matrix-validate-and-fixup
 static bool ValidateAndFixupMatrixInit(DOMMatrixInit& aMatrixInit,
                                        ErrorResult& aRv) {
-#define Check3DField(field, fieldName, defaultValue)  \
-  if ((field) != (defaultValue)) {                    \
-    if (!aMatrixInit.mIs2D.WasPassed()) {             \
-      aMatrixInit.mIs2D.Construct(false);             \
-      return true;                                    \
-    }                                                 \
-    if (aMatrixInit.mIs2D.Value()) {                  \
-      aRv.ThrowTypeError<MSG_MATRIX_INIT_EXCEEDS_2D>( \
-          NS_LITERAL_STRING(fieldName));              \
-      return false;                                   \
-    }                                                 \
+#define Check3DField(field, fieldName, defaultValue)             \
+  if ((field) != (defaultValue)) {                               \
+    if (!aMatrixInit.mIs2D.WasPassed()) {                        \
+      aMatrixInit.mIs2D.Construct(false);                        \
+      return true;                                               \
+    }                                                            \
+    if (aMatrixInit.mIs2D.Value()) {                             \
+      aRv.ThrowTypeError<MSG_MATRIX_INIT_EXCEEDS_2D>(fieldName); \
+      return false;                                              \
+    }                                                            \
   }
 
   if (!ValidateAndFixupMatrix2DInit(aMatrixInit, aRv)) {
@@ -190,7 +188,7 @@ already_AddRefed<DOMMatrixReadOnly> DOMMatrixReadOnly::FromMatrix(
 already_AddRefed<DOMMatrixReadOnly> DOMMatrixReadOnly::FromFloat32Array(
     const GlobalObject& aGlobal, const Float32Array& aArray32,
     ErrorResult& aRv) {
-  aArray32.ComputeLengthAndData();
+  aArray32.ComputeState();
 
   const int length = aArray32.Length();
   const bool is2D = length == 6;
@@ -204,7 +202,7 @@ already_AddRefed<DOMMatrixReadOnly> DOMMatrixReadOnly::FromFloat32Array(
 already_AddRefed<DOMMatrixReadOnly> DOMMatrixReadOnly::FromFloat64Array(
     const GlobalObject& aGlobal, const Float64Array& aArray64,
     ErrorResult& aRv) {
-  aArray64.ComputeLengthAndData();
+  aArray64.ComputeState();
 
   const int length = aArray64.Length();
   const bool is2D = length == 6;
@@ -637,7 +635,7 @@ already_AddRefed<DOMMatrix> DOMMatrix::FromMatrix(
 already_AddRefed<DOMMatrix> DOMMatrix::FromFloat32Array(
     const GlobalObject& aGlobal, const Float32Array& aArray32,
     ErrorResult& aRv) {
-  aArray32.ComputeLengthAndData();
+  aArray32.ComputeState();
 
   const int length = aArray32.Length();
   const bool is2D = length == 6;
@@ -650,7 +648,7 @@ already_AddRefed<DOMMatrix> DOMMatrix::FromFloat32Array(
 already_AddRefed<DOMMatrix> DOMMatrix::FromFloat64Array(
     const GlobalObject& aGlobal, const Float64Array& aArray64,
     ErrorResult& aRv) {
-  aArray64.ComputeLengthAndData();
+  aArray64.ComputeState();
 
   const int length = aArray64.Length();
   const bool is2D = length == 6;
@@ -724,7 +722,7 @@ static void SetDataInMatrix(DOMMatrixReadOnly* aMatrix, const T* aData,
     aMatrix->SetE(aData[4]);
     aMatrix->SetF(aData[5]);
   } else {
-    nsAutoString lengthStr;
+    nsAutoCString lengthStr;
     lengthStr.AppendInt(aLength);
     aRv.ThrowTypeError<MSG_MATRIX_INIT_LENGTH_WRONG>(lengthStr);
   }

dom/base/DOMMatrix.h

@@ -228,7 +228,7 @@ class DOMMatrixReadOnly : public nsWrapperCache {
   nsAutoPtr<gfx::MatrixDouble> mMatrix2D;
   nsAutoPtr<gfx::Matrix4x4Double> mMatrix3D;
 
-  virtual ~DOMMatrixReadOnly() {}
+  virtual ~DOMMatrixReadOnly() = default;
 
   /**
    * Sets data from a fully validated and fixed-up matrix init,
@@ -317,7 +317,7 @@ class DOMMatrix : public DOMMatrixReadOnly {
   DOMMatrix* InvertSelf();
   DOMMatrix* SetMatrixValue(const nsACString&, ErrorResult&);
 
-  virtual ~DOMMatrix() {}
+  virtual ~DOMMatrix() = default;
 
  private:
   DOMMatrix(nsISupports* aParent, bool is2D)

dom/base/DOMParser.cpp

@@ -37,7 +37,7 @@ DOMParser::DOMParser(nsIGlobalObject* aOwner, nsIPrincipal* aDocPrincipal,
   MOZ_ASSERT(aDocumentURI);
 }
 
-DOMParser::~DOMParser() {}
+DOMParser::~DOMParser() = default;
 
 // QueryInterface implementation for DOMParser
 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(DOMParser)
@@ -116,7 +116,7 @@ already_AddRefed<Document> DOMParser::ParseFromSafeString(const nsAString& aStr,
 already_AddRefed<Document> DOMParser::ParseFromBuffer(const Uint8Array& aBuf,
                                                       SupportedType aType,
                                                       ErrorResult& aRv) {
-  aBuf.ComputeLengthAndData();
+  aBuf.ComputeState();
   return ParseFromBuffer(MakeSpan(aBuf.Data(), aBuf.Length()), aType, aRv);
 }
 

dom/base/DOMPoint.h

@@ -57,7 +57,7 @@ class DOMPointReadOnly : public nsWrapperCache {
       JSStructuredCloneReader* aReader);
 
  protected:
-  virtual ~DOMPointReadOnly() {}
+  virtual ~DOMPointReadOnly() = default;
 
   // Shared implementation of ReadStructuredClone for DOMPoint and
   // DOMPointReadOnly.

dom/base/DOMQuad.cpp

@@ -28,7 +28,7 @@ DOMQuad::DOMQuad(nsISupports* aParent, CSSPoint aPoints[4]) : mParent(aParent) {
 
 DOMQuad::DOMQuad(nsISupports* aParent) : mParent(aParent) {}
 
-DOMQuad::~DOMQuad() {}
+DOMQuad::~DOMQuad() = default;
 
 JSObject* DOMQuad::WrapObject(JSContext* aCx,
                               JS::Handle<JSObject*> aGivenProto) {

dom/base/DOMRect.h

@@ -25,7 +25,7 @@ struct DOMRectInit;
 
 class DOMRectReadOnly : public nsISupports, public nsWrapperCache {
  protected:
-  virtual ~DOMRectReadOnly() {}
+  virtual ~DOMRectReadOnly() = default;
 
  public:
   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
@@ -129,11 +129,11 @@ class DOMRect final : public DOMRectReadOnly {
   }
 
  private:
-  ~DOMRect() {}
+  ~DOMRect() = default;
 };
 
 class DOMRectList final : public nsISupports, public nsWrapperCache {
-  ~DOMRectList() {}
+  ~DOMRectList() = default;
 
  public:
   explicit DOMRectList(nsISupports* aParent) : mParent(aParent) {}

dom/base/DOMRequest.h

@@ -81,7 +81,7 @@ class DOMRequest : public DOMEventTargetHelper {
 };
 
 class DOMRequestService final : public nsIDOMRequestService {
-  ~DOMRequestService() {}
+  ~DOMRequestService() = default;
 
  public:
   NS_DECL_ISUPPORTS

dom/base/DOMStringList.cpp

@@ -18,7 +18,7 @@ NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(DOMStringList)
   NS_INTERFACE_MAP_ENTRY(nsISupports)
 NS_INTERFACE_MAP_END
 
-DOMStringList::~DOMStringList() {}
+DOMStringList::~DOMStringList() = default;
 
 JSObject* DOMStringList::WrapObject(JSContext* aCx,
                                     JS::Handle<JSObject*> aGivenProto) {

dom/base/DOMStringList.h

@@ -55,9 +55,11 @@ class DOMStringList : public nsISupports, public nsWrapperCache {
   }
 
   bool Add(const nsAString& aName) {
-    // XXXbz mNames should really be a fallible array; otherwise this
-    // return value is meaningless.
-    return mNames.AppendElement(aName) != nullptr;
+    // XXXbz(Bug 1631374) mNames should really be a fallible array; otherwise
+    // this return value is meaningless. return mNames.AppendElement(aName) !=
+    // nullptr;
+    mNames.AppendElement(aName);
+    return true;
   }
 
   void Clear() { mNames.Clear(); }

dom/base/DirectionalityUtils.cpp

@@ -274,11 +274,14 @@ static bool AncestorChainCrossesShadowBoundary(nsIContent* aDescendant,
  * test for it separately, e.g. with DoesNotAffectDirectionOfAncestors.
  * It *does* include textarea, because even if a textarea has dir=auto, it has
  * unicode-bidi: plaintext and is handled automatically in bidi resolution.
+ * It also includes `input`, because it takes the `dir` value from its value
+ * attribute, instead of the child nodes.
  */
 static bool DoesNotParticipateInAutoDirection(const nsIContent* aContent) {
   mozilla::dom::NodeInfo* nodeInfo = aContent->NodeInfo();
   return ((!aContent->IsHTMLElement() || nodeInfo->Equals(nsGkAtoms::script) ||
            nodeInfo->Equals(nsGkAtoms::style) ||
+           nodeInfo->Equals(nsGkAtoms::input) ||
            nodeInfo->Equals(nsGkAtoms::textarea) ||
            aContent->IsInAnonymousSubtree())) &&
          !aContent->IsShadowRoot();
@@ -506,9 +509,7 @@ class nsTextNodeDirectionalityMap {
     aTextNode->SetHasTextNodeDirectionalityMap();
   }
 
-  ~nsTextNodeDirectionalityMap() {
-    MOZ_COUNT_DTOR(nsTextNodeDirectionalityMap);
-  }
+  MOZ_COUNTED_DTOR(nsTextNodeDirectionalityMap)
 
   static void nsTextNodeDirectionalityMapPropertyDestructor(
       void* aObject, nsAtom* aProperty, void* aPropertyValue, void* aData) {
@@ -536,7 +537,7 @@ class nsTextNodeDirectionalityMap {
 
     mElements.Remove(aElement);
     aElement->ClearHasDirAutoSet();
-    aElement->DeleteProperty(nsGkAtoms::dirAutoSetBy);
+    aElement->RemoveProperty(nsGkAtoms::dirAutoSetBy);
   }
 
   void RemoveEntryForProperty(Element* aElement) {
@@ -602,7 +603,7 @@ class nsTextNodeDirectionalityMap {
       nsTextNodeDirectionalityMap::AddEntryToMap(newTextNode, rootNode);
     } else {
       rootNode->ClearHasDirAutoSet();
-      rootNode->DeleteProperty(nsGkAtoms::dirAutoSetBy);
+      rootNode->RemoveProperty(nsGkAtoms::dirAutoSetBy);
     }
     return OpRemove;
   }
@@ -631,7 +632,7 @@ class nsTextNodeDirectionalityMap {
     mElements.EnumerateEntries(TakeEntries, &entries);
     for (Element* el : entries) {
       el->ClearHasDirAutoSet();
-      el->DeleteProperty(nsGkAtoms::dirAutoSetBy);
+      el->RemoveProperty(nsGkAtoms::dirAutoSetBy);
     }
   }
 

dom/base/DocGroup.cpp

@@ -50,6 +50,10 @@ DocGroup::DocGroup(TabGroup* aTabGroup, const nsACString& aKey)
     : mKey(aKey), mTabGroup(aTabGroup) {
   // This method does not add itself to mTabGroup->mDocGroups as the caller does
   // it for us.
+  if (StaticPrefs::dom_arena_allocator_enabled_AtStartup()) {
+    mArena = new mozilla::dom::DOMArena();
+  }
+
   mPerformanceCounter =
       new mozilla::PerformanceCounter(NS_LITERAL_CSTRING("DocGroup:") + aKey);
 }
@@ -60,6 +64,8 @@ DocGroup::~DocGroup() {
     nsIEventTarget* target = EventTargetFor(TaskCategory::Other);
     NS_ProxyRelease("DocGroup::mReactionsStack", target,
                     mReactionsStack.forget());
+
+    NS_ProxyRelease("DocGroup::mArena", target, mArena.forget());
   }
 
   mTabGroup->mDocGroups.RemoveEntry(mKey);
@@ -144,7 +150,7 @@ RefPtr<PerformanceInfoPromise> DocGroup::ReportPerformanceInfo() {
       ->Then(
           mainThread, __func__,
           [self, host, pid, windowID, duration, isTopLevel,
-           items](const PerformanceMemoryInfo& aMemoryInfo) {
+           items = std::move(items)](const PerformanceMemoryInfo& aMemoryInfo) {
             PerformanceInfo info =
                 PerformanceInfo(host, pid, windowID, duration,
                                 self->mPerformanceCounter->GetID(), false,

dom/base/DocGroup.h

@@ -56,6 +56,9 @@ class DocGroup final {
   RefPtr<PerformanceInfoPromise> ReportPerformanceInfo();
 
   TabGroup* GetTabGroup() { return mTabGroup; }
+
+  mozilla::dom::DOMArena* ArenaAllocator() { return mArena; }
+
   mozilla::dom::CustomElementReactionsStack* CustomElementReactionsStack() {
     MOZ_ASSERT(NS_IsMainThread());
     if (!mReactionsStack) {
@@ -124,6 +127,8 @@ class DocGroup final {
 
   RefPtr<mozilla::ThrottledEventQueue> mIframePostMessageQueue;
   nsTHashtable<nsUint64HashKey> mIframesUsedPostMessageQueue;
+
+  RefPtr<mozilla::dom::DOMArena> mArena;
 };
 
 }  // namespace dom

dom/base/Document.h

@@ -7,13 +7,15 @@
 #include "mozilla/EventStates.h"  // for EventStates
 #include "mozilla/FlushType.h"    // for enum
 #include "mozilla/MozPromise.h"   // for MozPromise
+#include "mozilla/FunctionRef.h"  // for FunctionRef
 #include "mozilla/Pair.h"         // for Pair
 #include "nsAutoPtr.h"            // for member
 #include "nsCOMArray.h"           // for member
 #include "nsCompatibility.h"      // for member
 #include "nsCOMPtr.h"             // for member
 #include "nsICookieSettings.h"
-#include "nsGkAtoms.h"  // for static class members
+#include "nsGkAtoms.h"           // for static class members
+#include "nsNameSpaceManager.h"  // for static class members
 #include "nsIApplicationCache.h"
 #include "nsIApplicationCacheContainer.h"
 #include "nsIContentViewer.h"
@@ -144,6 +146,7 @@ class ServoStyleSet;
 enum class StyleOrigin : uint8_t;
 class SMILAnimationController;
 enum class StyleCursorKind : uint8_t;
+enum class StylePrefersColorScheme : uint8_t;
 template <typename>
 class OwningNonNull;
 struct URLExtraData;
@@ -284,7 +287,7 @@ class DocHeaderData {
 };
 
 class ExternalResourceMap {
-  typedef bool (*SubDocEnumFunc)(Document& aDocument, void* aData);
+  using SubDocEnumFunc = FunctionRef<bool(Document&)>;
 
  public:
   /**
@@ -327,7 +330,7 @@ class ExternalResourceMap {
    * Enumerate the resource documents.  See
    * Document::EnumerateExternalResources.
    */
-  void EnumerateResources(SubDocEnumFunc aCallback, void* aData);
+  void EnumerateResources(SubDocEnumFunc aCallback);
 
   /**
    * Traverse ourselves for cycle-collection
@@ -362,7 +365,7 @@ class ExternalResourceMap {
 
  protected:
   class PendingLoad : public ExternalResourceLoad, public nsIStreamListener {
-    ~PendingLoad() {}
+    ~PendingLoad() = default;
 
    public:
     explicit PendingLoad(Document* aDisplayDocument)
@@ -393,7 +396,7 @@ class ExternalResourceMap {
   friend class PendingLoad;
 
   class LoadgroupCallbacks final : public nsIInterfaceRequestor {
-    ~LoadgroupCallbacks() {}
+    ~LoadgroupCallbacks() = default;
 
    public:
     explicit LoadgroupCallbacks(nsIInterfaceRequestor* aOtherCallbacks)
@@ -464,6 +467,8 @@ class Document : public nsINode,
                  public nsStubMutationObserver,
                  public DispatcherTrait,
                  public SupportsWeakPtr<Document> {
+  friend class DocumentOrShadowRoot;
+
  protected:
   explicit Document(const char* aContentType);
   virtual ~Document();
@@ -474,6 +479,12 @@ class Document : public nsINode,
  public:
   typedef dom::ExternalResourceMap::ExternalResourceLoad ExternalResourceLoad;
   typedef dom::ReferrerPolicy ReferrerPolicyEnum;
+  using AdoptedStyleSheetCloneCache =
+      nsRefPtrHashtable<nsPtrHashKey<const StyleSheet>, StyleSheet>;
+
+  // nsINode overrides the new operator for DOM Arena allocation.
+  // to use the default one, we need to bring it back again
+  void* operator new(size_t aSize) { return ::operator new(aSize); }
 
   /**
    * Called when XPCOM shutdown.
@@ -565,6 +576,8 @@ class Document : public nsINode,
     return mIntrinsicStoragePrincipal;
   }
 
+  void ClearActiveStoragePrincipal() { mActiveStoragePrincipal = nullptr; }
+
   nsIPrincipal* GetContentBlockingAllowListPrincipal() const {
     return mContentBlockingAllowListPrincipal;
   }
@@ -1103,6 +1116,14 @@ class Document : public nsINode,
     mHasUnsafeEvalCSP = aHasUnsafeEvalCSP;
   }
 
+  /**
+   * Returns true if the document holds a CSP
+   * delivered through an HTTP Header.
+   */
+  bool GetHasCSPDeliveredThroughHeader() {
+    return mHasCSPDeliveredThroughHeader;
+  }
+
   /**
    * Get the content blocking log.
    */
@@ -1779,7 +1800,7 @@ class Document : public nsINode,
 
     nsExpirationState* GetExpirationState() { return &mState; }
 
-    ~SelectorCacheKey() { MOZ_COUNT_DTOR(SelectorCacheKey); }
+    MOZ_COUNTED_DTOR(SelectorCacheKey)
   };
 
   class SelectorCacheKeyDeleter;
@@ -1878,11 +1899,6 @@ class Document : public nsINode,
     InsertSheetAt(SheetCount(), *aSheet);
   }
 
-  /**
-   * Remove a stylesheet from the document
-   */
-  void RemoveStyleSheet(StyleSheet&);
-
   /**
    * Notify the document that the applicable state of the sheet changed
    * and that observers should be notified and style sets updated
@@ -1906,8 +1922,6 @@ class Document : public nsINode,
     return mAdditionalSheets[eAuthorSheet].SafeElementAt(0);
   }
 
-  void AppendAdoptedStyleSheet(StyleSheet& aSheet);
-
   /**
    * Returns the index that aSheet should be inserted at to maintain document
    * ordering.
@@ -2028,14 +2042,14 @@ class Document : public nsINode,
   void RemoveFromNameTable(Element* aElement, nsAtom* aName);
 
   /**
-   * Returns all elements in the fullscreen stack in the insertion order.
+   * Returns all elements in the top layer in the insertion order.
    */
-  nsTArray<Element*> GetFullscreenStack() const;
+  nsTArray<Element*> GetTopLayer() const;
 
   /**
    * Asynchronously requests that the document make aElement the fullscreen
    * element, and move into fullscreen mode. The current fullscreen element
-   * (if any) is pushed onto the fullscreen element stack, and it can be
+   * (if any) is pushed onto the top layer, and it can be
    * returned to fullscreen status by calling RestorePreviousFullscreenState().
    *
    * Note that requesting fullscreen in a document also makes the element which
@@ -2048,25 +2062,30 @@ class Document : public nsINode,
   // Do the "fullscreen element ready check" from the fullscreen spec.
   // It returns true if the given element is allowed to go into fullscreen.
   // It is responsive to dispatch "fullscreenerror" event when necessary.
-  bool FullscreenElementReadyCheck(const FullscreenRequest&);
+  bool FullscreenElementReadyCheck(FullscreenRequest&);
 
   // This is called asynchronously by Document::AsyncRequestFullscreen()
   // to move this document into fullscreen mode if allowed.
   void RequestFullscreen(UniquePtr<FullscreenRequest> aRequest);
 
-  // Removes all elements from the fullscreen stack, removing full-scren
-  // styles from the top element in the stack.
+  // Removes all the elements with fullscreen flag set from the top layer, and
+  // clears their fullscreen flag.
   void CleanupFullscreenState();
 
-  // Pushes aElement onto the fullscreen stack, and removes fullscreen styles
-  // from the former fullscreen stack top, and its ancestors, and applies the
-  // styles to aElement. aElement becomes the new "fullscreen element".
-  bool FullscreenStackPush(Element* aElement);
+  // Pushes aElement onto the top layer
+  bool TopLayerPush(Element* aElement);
 
-  // Remove the top element from the fullscreen stack. Removes the fullscreen
-  // styles from the former top element, and applies them to the new top
-  // element, if there is one.
-  void FullscreenStackPop();
+  // Removes the topmost element which have aPredicate return true from the top
+  // layer. The removed element, if any, is returned.
+  Element* TopLayerPop(FunctionRef<bool(Element*)> aPredicateFunc);
+
+  // Pops the fullscreen element from the top layer and clears its
+  // fullscreen flag.
+  void UnsetFullscreenElement();
+
+  // Pushes the given element into the top of top layer and set fullscreen
+  // flag.
+  bool SetFullscreenElement(Element* aElement);
 
   /**
    * Called when a frame in a child process has entered fullscreen or when a
@@ -2078,7 +2097,7 @@ class Document : public nsINode,
 
   /**
    * Called when a frame in a remote child document has rolled back fullscreen
-   * so that all its fullscreen element stacks are empty; we must continue the
+   * so that all its top layer are empty; we must continue the
    * rollback in this parent process' doc tree branch which is fullscreen.
    * Note that only one branch of the document tree can have its documents in
    * fullscreen state at one time. We're in inconsistent state if a
@@ -2107,6 +2126,8 @@ class Document : public nsINode,
    */
   Document* GetFullscreenRoot();
 
+  size_t CountFullscreenElements() const;
+
   /**
    * Sets the fullscreen root to aRoot. This stores a weak reference to aRoot
    * in this document.
@@ -2412,8 +2433,8 @@ class Document : public nsINode,
    */
   int32_t GetDefaultNamespaceID() const { return mDefaultElementType; }
 
-  void DeleteAllProperties();
-  void DeleteAllPropertiesFor(nsINode* aNode);
+  void RemoveAllProperties();
+  void RemoveAllPropertiesFor(nsINode* aNode);
 
   nsPropertyTable& PropertyTable() { return mPropertyTable; }
 
@@ -2438,8 +2459,8 @@ class Document : public nsINode,
    * The enumerator callback should return true to continue enumerating, or
    * false to stop.  This will never get passed a null aDocument.
    */
-  typedef bool (*SubDocEnumFunc)(Document&, void* aData);
-  void EnumerateSubDocuments(SubDocEnumFunc aCallback, void* aData);
+  using SubDocEnumFunc = FunctionRef<bool(Document&)>;
+  void EnumerateSubDocuments(SubDocEnumFunc aCallback);
 
   /**
    * Collect all the descendant documents for which |aCalback| returns true.
@@ -2768,7 +2789,7 @@ class Document : public nsINode,
    * The enumerator callback should return true to continue enumerating, or
    * false to stop.  This callback will never get passed a null aDocument.
    */
-  void EnumerateExternalResources(SubDocEnumFunc aCallback, void* aData);
+  void EnumerateExternalResources(SubDocEnumFunc aCallback);
 
   dom::ExternalResourceMap& ExternalResourceMap() {
     return mExternalResourceMap;
@@ -2836,9 +2857,8 @@ class Document : public nsINode,
   void RegisterActivityObserver(nsISupports* aSupports);
   bool UnregisterActivityObserver(nsISupports* aSupports);
   // Enumerate all the observers in mActivityObservers by the aEnumerator.
-  typedef void (*ActivityObserverEnumerator)(nsISupports*, void*);
-  void EnumerateActivityObservers(ActivityObserverEnumerator aEnumerator,
-                                  void* aData);
+  using ActivityObserverEnumerator = FunctionRef<void(nsISupports*)>;
+  void EnumerateActivityObservers(ActivityObserverEnumerator aEnumerator);
 
   // Indicates whether mAnimationController has been (lazily) initialized.
   // If this returns true, we're promising that GetAnimationController()
@@ -2986,7 +3006,7 @@ class Document : public nsINode,
    * Note that static documents are also "loaded as data" (if this method
    * returns true, IsLoadedAsData() will also return true).
    */
-  bool IsStaticDocument() { return mIsStaticDocument; }
+  bool IsStaticDocument() const { return mIsStaticDocument; }
 
   /**
    * Clones the document along with any subdocuments, stylesheet, etc.
@@ -3490,6 +3510,7 @@ class Document : public nsINode,
                mozilla::ErrorResult& rv);
   Nullable<WindowProxyHolder> GetDefaultView() const;
   Element* GetActiveElement();
+  nsIContent* GetUnretargetedFocusedContent() const;
   bool HasFocus(ErrorResult& rv) const;
   void GetDesignMode(nsAString& aDesignMode);
   void SetDesignMode(const nsAString& aDesignMode,
@@ -3526,7 +3547,9 @@ class Document : public nsINode,
   nsIURI* GetDocumentURIObject() const;
   // Not const because all the fullscreen goop is not const
   bool FullscreenEnabled(CallerType aCallerType);
-  Element* FullscreenStackTop();
+  Element* GetTopLayerTop();
+  // Return the fullscreen element in the top layer
+  Element* GetUnretargetedFullScreenElement();
   bool Fullscreen() { return !!GetFullscreenElement(); }
   already_AddRefed<Promise> ExitFullscreen(ErrorResult&);
   void ExitPointerLock() { UnlockPointer(this); }
@@ -3718,16 +3741,6 @@ class Document : public nsINode,
 
   bool IsSynthesized();
 
-  void AddToVisibleContentHeuristic(size_t aNumber) {
-    if (MOZ_UNLIKELY(SIZE_MAX - mVisibleContentHeuristic < aNumber)) {
-      mVisibleContentHeuristic = SIZE_MAX;
-    } else {
-      mVisibleContentHeuristic += aNumber;
-    }
-  }
-
-  size_t GetVisibleContentHeuristic() const { return mVisibleContentHeuristic; }
-
   // Called to track whether this document has had any interaction.
   // This is used to track whether we should permit "beforeunload".
   void SetUserHasInteracted();
@@ -3777,6 +3790,8 @@ class Document : public nsINode,
     return mDocGroup;
   }
 
+  DocGroup* GetDocGroupOrCreate();
+
   /**
    * If we're a sub-document, the parent document's layout can affect our style
    * and layout (due to the viewport size, viewport units, media queries...).
@@ -4052,6 +4067,9 @@ class Document : public nsINode,
   bool InRDMPane() const { return mInRDMPane; }
   void SetInRDMPane(bool aInRDMPane) { mInRDMPane = aInRDMPane; }
 
+  // CSS prefers-color-scheme media feature for this document.
+  StylePrefersColorScheme PrefersColorScheme() const;
+
   // Returns true if we use overlay scrollbars on the system wide or on the
   // given document.
   static bool UseOverlayScrollbars(const Document* aDocument);
@@ -4060,10 +4078,6 @@ class Document : public nsINode,
 
   static bool AutomaticStorageAccessCanBeGranted(nsIPrincipal* aPrincipal);
 
-  void SetAdoptedStyleSheets(
-      const Sequence<OwningNonNull<StyleSheet>>& aAdoptedStyleSheets,
-      ErrorResult& aRv);
-
  protected:
   void DoUpdateSVGUseElementShadowTrees();
 
@@ -4104,8 +4118,6 @@ class Document : public nsINode,
   bool ApplyFullscreen(UniquePtr<FullscreenRequest>);
 
   void RemoveDocStyleSheetsFromStyleSets();
-  void RemoveStyleSheetsFromStyleSets(
-      const nsTArray<RefPtr<StyleSheet>>& aSheets, StyleOrigin);
   void ResetStylesheetsToURI(nsIURI* aURI);
   void FillStyleSet();
   void FillStyleSetUserAndUASheets();
@@ -4118,8 +4130,8 @@ class Document : public nsINode,
   }
   void AddContentEditableStyleSheetsToStyleSet(bool aDesignMode);
   void RemoveContentEditableStyleSheets();
-  void AddStyleSheetToStyleSets(StyleSheet* aSheet);
-  void RemoveStyleSheetFromStyleSets(StyleSheet* aSheet);
+  void AddStyleSheetToStyleSets(StyleSheet&);
+  void RemoveStyleSheetFromStyleSets(StyleSheet&);
   void NotifyStyleSheetApplicableStateChanged();
   // Just like EnableStyleSheetsForSet, but doesn't check whether
   // aSheetSet is null and allows the caller to control whether to set
@@ -4564,6 +4576,9 @@ class Document : public nsINode,
   // True if a document load has a CSP with unsafe-inline attached.
   bool mHasUnsafeInlineCSP : 1;
 
+  // True if the document has a CSP delivered throuh a header
+  bool mHasCSPDeliveredThroughHeader : 1;
+
   // True if DisallowBFCaching has been called on this document.
   bool mBFCacheDisallowed : 1;
 
@@ -4917,16 +4932,6 @@ class Document : public nsINode,
   // Array of observers
   nsTObserverArray<nsIDocumentObserver*> mObservers;
 
-  // An ever-increasing heuristic number that is higher the more content is
-  // likely to be visible in the page.
-  //
-  // Right now it effectively measures amount of text content that has ever been
-  // connected to the document in some way, and is not under a <script> or
-  // <style>.
-  //
-  // Note that this is only measured during load.
-  size_t mVisibleContentHeuristic = 0;
-
   // Whether the user has interacted with the document or not:
   bool mUserHasInteracted;
 
@@ -5019,10 +5024,8 @@ class Document : public nsINode,
   // Array of intersection observers
   nsTHashtable<nsPtrHashKey<DOMIntersectionObserver>> mIntersectionObservers;
 
-  // Stack of fullscreen elements. When we request fullscreen we push the
-  // fullscreen element onto this stack, and when we cancel fullscreen we
-  // pop one off this stack, restoring the previous fullscreen state
-  nsTArray<nsWeakPtr> mFullscreenStack;
+  // Stack of top layer elements.
+  nsTArray<nsWeakPtr> mTopLayer;
 
   // The root of the doc tree in which this document is in. This is only
   // non-null when this document is in fullscreen mode.
@@ -5170,6 +5173,11 @@ class Document : public nsINode,
   // The principal to use for the storage area of this document.
   nsCOMPtr<nsIPrincipal> mIntrinsicStoragePrincipal;
 
+  // The cached storage principal for this document.
+  // This is mutable so that we can keep EffectiveStoragePrincipal() const
+  // which is required due to its CloneDocHelper() call site.  :-(
+  mutable nsCOMPtr<nsIPrincipal> mActiveStoragePrincipal;
+
   // The principal to use for the content blocking allow list.
   nsCOMPtr<nsIPrincipal> mContentBlockingAllowListPrincipal;
 

dom/base/DocumentFragment.h

@@ -82,7 +82,7 @@ class DocumentFragment : public FragmentOrElement {
 #endif
 
  protected:
-  virtual ~DocumentFragment() {}
+  virtual ~DocumentFragment() = default;
 
   nsresult Clone(dom::NodeInfo* aNodeInfo, nsINode** aResult) const override;
   RefPtr<Element> mHost;

dom/base/DocumentOrShadowRoot.cpp

@@ -71,35 +71,44 @@ StyleSheetList* DocumentOrShadowRoot::StyleSheets() {
 }
 
 void DocumentOrShadowRoot::InsertSheetAt(size_t aIndex, StyleSheet& aSheet) {
-  aSheet.SetAssociatedDocumentOrShadowRoot(
-      this, StyleSheet::OwnedByDocumentOrShadowRoot);
+  aSheet.SetAssociatedDocumentOrShadowRoot(this);
   mStyleSheets.InsertElementAt(aIndex, &aSheet);
 }
 
-void DocumentOrShadowRoot::InsertAdoptedSheetAt(size_t aIndex,
-                                                StyleSheet& aSheet) {
-  mAdoptedStyleSheets.InsertElementAt(aIndex, &aSheet);
-}
-
-already_AddRefed<StyleSheet> DocumentOrShadowRoot::RemoveSheet(
-    StyleSheet& aSheet) {
+void DocumentOrShadowRoot::RemoveStyleSheet(StyleSheet& aSheet) {
   auto index = mStyleSheets.IndexOf(&aSheet);
   if (index == mStyleSheets.NoIndex) {
-    return nullptr;
+    // We should only hit this case if we are unlinking
+    // in which case mStyleSheets should be cleared.
+    MOZ_ASSERT(mKind != Kind::Document ||
+               AsNode().AsDocument()->InUnlinkOrDeletion());
+    MOZ_ASSERT(mStyleSheets.IsEmpty());
+    return;
   }
   RefPtr<StyleSheet> sheet = std::move(mStyleSheets[index]);
   mStyleSheets.RemoveElementAt(index);
+  RemoveSheetFromStylesIfApplicable(*sheet);
   sheet->ClearAssociatedDocumentOrShadowRoot();
-  return sheet.forget();
+}
+
+void DocumentOrShadowRoot::RemoveSheetFromStylesIfApplicable(
+    StyleSheet& aSheet) {
+  if (!aSheet.IsApplicable()) {
+    return;
+  }
+  if (mKind == Kind::Document) {
+    AsNode().AsDocument()->RemoveStyleSheetFromStyleSets(aSheet);
+  } else {
+    MOZ_ASSERT(AsNode().IsShadowRoot());
+    static_cast<ShadowRoot&>(AsNode()).RemoveSheetFromStyles(aSheet);
+  }
 }
 
 // https://wicg.github.io/construct-stylesheets/#dom-documentorshadowroot-adoptedstylesheets
-void DocumentOrShadowRoot::EnsureAdoptedSheetsAreValid(
+void DocumentOrShadowRoot::SetAdoptedStyleSheets(
     const Sequence<OwningNonNull<StyleSheet>>& aAdoptedStyleSheets,
     ErrorResult& aRv) {
-  nsTHashtable<nsPtrHashKey<const StyleSheet>> set(
-      aAdoptedStyleSheets.Length());
-
+  Document& doc = *AsNode().OwnerDoc();
   for (const OwningNonNull<StyleSheet>& sheet : aAdoptedStyleSheets) {
     // 2.1 Check if all sheets are constructed, else throw NotAllowedError
     if (!sheet->IsConstructed()) {
@@ -109,23 +118,117 @@ void DocumentOrShadowRoot::EnsureAdoptedSheetsAreValid(
     }
     // 2.2 Check if all sheets' constructor documents match the
     // DocumentOrShadowRoot's node document, else throw NotAlloweError
-    if (!sheet->ConstructorDocumentMatches(AsNode().OwnerDoc())) {
+    if (!sheet->ConstructorDocumentMatches(doc)) {
       return aRv.ThrowNotAllowedError(
           "Each adopted style sheet's constructor document must match the "
           "document or shadow root's node document");
     }
+  }
 
-    // FIXME(nordzilla): This is temporary code to disallow duplicate sheets.
-    // This exists to ensure that the fuzzers aren't blocked.
-    // This code will eventually be removed.
-    // https://bugzilla.mozilla.org/show_bug.cgi?id=1617302
-    if (!set.EnsureInserted(sheet.get())) {
-      return aRv.ThrowNotAllowedError(
-          "Temporarily disallowing duplicate stylesheets.");
+  auto* shadow = ShadowRoot::FromNode(AsNode());
+  MOZ_ASSERT((mKind == Kind::ShadowRoot) == !!shadow);
+
+  StyleSheetSet set(aAdoptedStyleSheets.Length());
+  size_t commonPrefix = 0;
+
+  // Find the index at which the new array differs from the old array.
+  // We don't want to do extra work for the sheets that both arrays have.
+  size_t min =
+      std::min(aAdoptedStyleSheets.Length(), mAdoptedStyleSheets.Length());
+  for (size_t i = 0; i < min; ++i) {
+    if (aAdoptedStyleSheets[i] != mAdoptedStyleSheets[i]) {
+      break;
+    }
+    ++commonPrefix;
+    set.PutEntry(mAdoptedStyleSheets[i]);
+  }
+
+  // Try to truncate the sheets to a common prefix.
+  // If the prefix contains duplicates of sheets that we are removing,
+  // we are just going to re-build everything from scratch.
+  if (commonPrefix != mAdoptedStyleSheets.Length()) {
+    StyleSheetSet removedSet(mAdoptedStyleSheets.Length() - commonPrefix);
+    for (size_t i = mAdoptedStyleSheets.Length(); i != commonPrefix; --i) {
+      StyleSheet* sheetToRemove = mAdoptedStyleSheets.ElementAt(i - 1);
+      if (MOZ_UNLIKELY(set.Contains(sheetToRemove))) {
+        // Fixing duplicate sheets would require insertions/removals from the
+        // style set. We may as well just rebuild the whole thing from scratch.
+        set.Clear();
+        // Note that setting this to zero means we'll continue the loop until
+        // all the sheets are cleared.
+        commonPrefix = 0;
+      }
+      if (MOZ_LIKELY(removedSet.EnsureInserted(sheetToRemove))) {
+        RemoveSheetFromStylesIfApplicable(*sheetToRemove);
+        sheetToRemove->RemoveAdopter(*this);
+      }
+    }
+    mAdoptedStyleSheets.TruncateLength(commonPrefix);
+  }
+
+  // 3. Set the adopted style sheets to the new sheets
+  mAdoptedStyleSheets.SetCapacity(aAdoptedStyleSheets.Length());
+
+  // Only add sheets that are not already in the common prefix.
+  for (const auto& sheet : MakeSpan(aAdoptedStyleSheets).From(commonPrefix)) {
+    if (MOZ_UNLIKELY(!set.EnsureInserted(sheet))) {
+      // The idea is that this case is rare, so we pay the price of removing the
+      // old sheet from the styles and append it later rather than the other way
+      // around.
+      RemoveSheetFromStylesIfApplicable(*sheet);
+    } else {
+      sheet->AddAdopter(*this);
+    }
+    mAdoptedStyleSheets.AppendElement(sheet);
+    if (sheet->IsApplicable()) {
+      if (mKind == Kind::Document) {
+        doc.AddStyleSheetToStyleSets(*sheet);
+      } else {
+        shadow->InsertSheetIntoAuthorData(mAdoptedStyleSheets.Length() - 1,
+                                          *sheet, mAdoptedStyleSheets);
+      }
     }
   }
 }
 
+void DocumentOrShadowRoot::ClearAdoptedStyleSheets() {
+  EnumerateUniqueAdoptedStyleSheetsBackToFront([&](StyleSheet& aSheet) {
+    RemoveSheetFromStylesIfApplicable(aSheet);
+    aSheet.RemoveAdopter(*this);
+  });
+  mAdoptedStyleSheets.Clear();
+}
+
+void DocumentOrShadowRoot::CloneAdoptedSheetsFrom(
+    const DocumentOrShadowRoot& aSource) {
+  if (!aSource.AdoptedSheetCount()) {
+    return;
+  }
+  Sequence<OwningNonNull<StyleSheet>> list;
+  if (!list.SetCapacity(mAdoptedStyleSheets.Length(), fallible)) {
+    return;
+  }
+
+  Document& ownerDoc = *AsNode().OwnerDoc();
+  const Document& sourceDoc = *aSource.AsNode().OwnerDoc();
+  auto* clonedSheetMap = static_cast<Document::AdoptedStyleSheetCloneCache*>(
+      sourceDoc.GetProperty(nsGkAtoms::adoptedsheetclones));
+  MOZ_ASSERT(clonedSheetMap);
+
+  for (const StyleSheet* sheet : aSource.mAdoptedStyleSheets) {
+    RefPtr<StyleSheet> clone = clonedSheetMap->LookupForAdd(sheet).OrInsert(
+        [&] { return sheet->CloneAdoptedSheet(ownerDoc); });
+    MOZ_ASSERT(clone);
+    MOZ_DIAGNOSTIC_ASSERT(clone->ConstructorDocumentMatches(ownerDoc));
+    DebugOnly<bool> succeeded = list.AppendElement(std::move(clone), fallible);
+    MOZ_ASSERT(succeeded);
+  }
+
+  ErrorResult rv;
+  SetAdoptedStyleSheets(list, rv);
+  MOZ_ASSERT(!rv.Failed());
+}
+
 Element* DocumentOrShadowRoot::GetElementById(const nsAString& aElementId) {
   if (MOZ_UNLIKELY(aElementId.IsEmpty())) {
     nsContentUtils::ReportEmptyGetElementByIdArg(AsNode().OwnerDoc());
@@ -184,25 +287,13 @@ nsIContent* DocumentOrShadowRoot::Retarget(nsIContent* aContent) const {
 }
 
 Element* DocumentOrShadowRoot::GetRetargetedFocusedElement() {
-  if (nsCOMPtr<nsPIDOMWindowOuter> window = AsNode().OwnerDoc()->GetWindow()) {
-    nsCOMPtr<nsPIDOMWindowOuter> focusedWindow;
-    nsIContent* focusedContent = nsFocusManager::GetFocusedDescendant(
-        window, nsFocusManager::eOnlyCurrentWindow,
-        getter_AddRefs(focusedWindow));
-    // be safe and make sure the element is from this document
-    if (focusedContent && focusedContent->OwnerDoc() == AsNode().OwnerDoc()) {
-      if (focusedContent->ChromeOnlyAccess()) {
-        focusedContent = focusedContent->FindFirstNonChromeOnlyAccessContent();
-      }
-
-      if (focusedContent) {
-        if (nsIContent* retarget = Retarget(focusedContent)) {
-          return retarget->AsElement();
-        }
-      }
-    }
+  auto* content = AsNode().OwnerDoc()->GetUnretargetedFocusedContent();
+  if (!content) {
+    return nullptr;
+  }
+  if (nsIContent* retarget = Retarget(content)) {
+    return retarget->AsElement();
   }
-
   return nullptr;
 }
 
@@ -225,7 +316,7 @@ Element* DocumentOrShadowRoot::GetFullscreenElement() {
     return nullptr;
   }
 
-  Element* element = AsNode().OwnerDoc()->FullscreenStackTop();
+  Element* element = AsNode().OwnerDoc()->GetUnretargetedFullScreenElement();
   NS_ASSERTION(!element || element->State().HasState(NS_EVENT_STATE_FULLSCREEN),
                "Fullscreen element should have fullscreen styles applied");
 
@@ -510,7 +601,7 @@ void DocumentOrShadowRoot::GetAnimations(
        child = child->GetNextSibling()) {
     if (RefPtr<Element> element = Element::FromNode(child)) {
       nsTArray<RefPtr<Animation>> result;
-      element->GetAnimations(options, result, Element::Flush::No);
+      element->GetAnimationsWithoutFlush(options, result);
       aAnimations.AppendElements(std::move(result));
     }
   }
@@ -660,7 +751,9 @@ nsRadioGroupStruct* DocumentOrShadowRoot::GetOrCreateRadioGroup(
 int32_t DocumentOrShadowRoot::StyleOrderIndexOfSheet(
     const StyleSheet& aSheet) const {
   if (aSheet.IsConstructed()) {
-    int32_t index = mAdoptedStyleSheets.IndexOf(&aSheet);
+    // NOTE: constructable sheets can have duplicates, so we need to start
+    // looking from behind.
+    int32_t index = mAdoptedStyleSheets.LastIndexOf(&aSheet);
     return (index < 0) ? index : index + SheetCount();
   }
   return mStyleSheets.IndexOf(&aSheet);
@@ -677,26 +770,27 @@ void DocumentOrShadowRoot::Traverse(DocumentOrShadowRoot* tmp,
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mDOMStyleSheets)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mAdoptedStyleSheets)
 
-  auto NoteSheets = [tmp, &cb = cb](nsTArray<RefPtr<StyleSheet>>& sheetList) {
-    for (StyleSheet* sheet : sheetList) {
-      if (!sheet->IsApplicable()) {
-        continue;
-      }
-      // The style set or mServoStyles keep more references to it if the sheet
-      // is applicable.
-      if (tmp->mKind == Kind::ShadowRoot) {
-        NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "mServoStyles->sheets[i]");
-        cb.NoteXPCOMChild(sheet);
-      } else if (tmp->AsNode().AsDocument()->StyleSetFilled()) {
-        NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(
-            cb, "mStyleSet->mRawSet.stylist.stylesheets.author[i]");
-        cb.NoteXPCOMChild(sheet);
-      }
+  auto NoteSheetIfApplicable = [&](StyleSheet& aSheet) {
+    if (!aSheet.IsApplicable()) {
+      return;
+    }
+    // The style set or mServoStyles keep more references to it if the sheet
+    // is applicable.
+    if (tmp->mKind == Kind::ShadowRoot) {
+      NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "mServoStyles->sheets[i]");
+      cb.NoteXPCOMChild(&aSheet);
+    } else if (tmp->AsNode().AsDocument()->StyleSetFilled()) {
+      NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(
+          cb, "mStyleSet->mRawSet.stylist.stylesheets.author[i]");
+      cb.NoteXPCOMChild(&aSheet);
     }
   };
 
-  NoteSheets(tmp->mStyleSheets);
-  NoteSheets(tmp->mAdoptedStyleSheets);
+  for (auto& sheet : tmp->mStyleSheets) {
+    NoteSheetIfApplicable(*sheet);
+  }
+
+  tmp->EnumerateUniqueAdoptedStyleSheetsBackToFront(NoteSheetIfApplicable);
 
   for (auto iter = tmp->mIdentifierMap.ConstIter(); !iter.Done(); iter.Next()) {
     iter.Get()->Traverse(&cb);
@@ -719,7 +813,12 @@ void DocumentOrShadowRoot::Traverse(DocumentOrShadowRoot* tmp,
 
 void DocumentOrShadowRoot::Unlink(DocumentOrShadowRoot* tmp) {
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mDOMStyleSheets);
-  for (RefPtr<StyleSheet>& sheet : tmp->mAdoptedStyleSheets) {
+  for (StyleSheet* sheet : tmp->mStyleSheets) {
+    sheet->ClearAssociatedDocumentOrShadowRoot();
+    tmp->RemoveSheetFromStylesIfApplicable(*sheet);
+  }
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mStyleSheets);
+  for (StyleSheet* sheet : tmp->mAdoptedStyleSheets) {
     sheet->RemoveAdopter(*tmp);
   }
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mAdoptedStyleSheets);

dom/base/DocumentOrShadowRoot.h

@@ -86,6 +86,8 @@ class DocumentOrShadowRoot {
 
   void GetAdoptedStyleSheets(nsTArray<RefPtr<StyleSheet>>&) const;
 
+  void RemoveStyleSheet(StyleSheet&);
+
   Element* GetElementById(const nsAString& aElementId);
 
   /**
@@ -219,16 +221,38 @@ class DocumentOrShadowRoot {
 
   nsIContent* Retarget(nsIContent* aContent) const;
 
- protected:
-  // Returns the reference to the sheet, if found in mStyleSheets.
-  already_AddRefed<StyleSheet> RemoveSheet(StyleSheet& aSheet);
-  void InsertSheetAt(size_t aIndex, StyleSheet& aSheet);
-  void InsertAdoptedSheetAt(size_t aIndex, StyleSheet& aSheet);
-
-  void EnsureAdoptedSheetsAreValid(
+  void SetAdoptedStyleSheets(
       const Sequence<OwningNonNull<StyleSheet>>& aAdoptedStyleSheets,
       ErrorResult& aRv);
 
+  // This is needed because ServoStyleSet / ServoAuthorData don't deal with
+  // duplicate stylesheets (and it's unclear we'd want to support that as it'd
+  // be a bunch of duplicate work), while adopted stylesheets do need to deal
+  // with them.
+  template <typename Callback>
+  void EnumerateUniqueAdoptedStyleSheetsBackToFront(Callback aCallback) {
+    StyleSheetSet set(mAdoptedStyleSheets.Length());
+    for (StyleSheet* sheet : Reversed(mAdoptedStyleSheets)) {
+      if (MOZ_UNLIKELY(!set.EnsureInserted(sheet))) {
+        continue;
+      }
+      aCallback(*sheet);
+    }
+  }
+
+ protected:
+  using StyleSheetSet = nsTHashtable<nsPtrHashKey<const StyleSheet>>;
+  void RemoveSheetFromStylesIfApplicable(StyleSheet&);
+  void ClearAdoptedStyleSheets();
+
+  /**
+   * Clone's the argument's adopted style sheets into this.
+   * This should only be used when cloning a static document for printing.
+   */
+  void CloneAdoptedSheetsFrom(const DocumentOrShadowRoot&);
+
+  void InsertSheetAt(size_t aIndex, StyleSheet& aSheet);
+
   void AddSizeOfExcludingThis(nsWindowSizes&) const;
   void AddSizeOfOwnedSheetArrayExcludingThis(
       nsWindowSizes&, const nsTArray<RefPtr<StyleSheet>>&) const;
@@ -243,8 +267,10 @@ class DocumentOrShadowRoot {
   nsTArray<RefPtr<StyleSheet>> mStyleSheets;
   RefPtr<StyleSheetList> mDOMStyleSheets;
 
-  // Style sheets that are adopted by assinging to the `adoptedStyleSheets`
-  // WebIDL atribute. These can only be constructed stylesheets.
+  /**
+   * Style sheets that are adopted by assinging to the `adoptedStyleSheets`
+   * WebIDL atribute. These can only be constructed stylesheets.
+   */
   nsTArray<RefPtr<StyleSheet>> mAdoptedStyleSheets;
 
   /*

dom/base/DocumentType.cpp

@@ -25,8 +25,9 @@ already_AddRefed<mozilla::dom::DocumentType> NS_NewDOMDocumentType(
       nsGkAtoms::documentTypeNodeName, nullptr, kNameSpaceID_None,
       nsINode::DOCUMENT_TYPE_NODE, aName);
 
-  RefPtr<mozilla::dom::DocumentType> docType = new mozilla::dom::DocumentType(
-      ni.forget(), aPublicId, aSystemId, aInternalSubset);
+  RefPtr<mozilla::dom::DocumentType> docType =
+      new (aNodeInfoManager) mozilla::dom::DocumentType(
+          ni.forget(), aPublicId, aSystemId, aInternalSubset);
   return docType.forget();
 }
 
@@ -73,8 +74,8 @@ void DocumentType::GetInternalSubset(nsAString& aInternalSubset) const {
 
 already_AddRefed<CharacterData> DocumentType::CloneDataNode(
     mozilla::dom::NodeInfo* aNodeInfo, bool aCloneText) const {
-  return do_AddRef(new DocumentType(do_AddRef(aNodeInfo), mPublicId, mSystemId,
-                                    mInternalSubset));
+  return do_AddRef(new (aNodeInfo->NodeInfoManager()) DocumentType(
+      do_AddRef(aNodeInfo), mPublicId, mSystemId, mInternalSubset));
 }
 
 }  // namespace dom

dom/base/Element.cpp

@@ -24,6 +24,7 @@
 #include "mozilla/dom/MutationObservers.h"
 #include "mozilla/dom/ScriptLoader.h"
 #include "mozilla/dom/Text.h"
+#include "mozilla/dom/nsCSPContext.h"
 #include "mozilla/gfx/Matrix.h"
 #include "nsAtom.h"
 #include "nsDOMAttributeMap.h"
@@ -260,8 +261,7 @@ Element::QueryInterface(REFNSIID aIID, void** aInstancePtr) {
 }
 
 EventStates Element::IntrinsicState() const {
-  return IsEditable() ? NS_EVENT_STATE_MOZ_READWRITE
-                      : NS_EVENT_STATE_MOZ_READONLY;
+  return IsEditable() ? NS_EVENT_STATE_READWRITE : NS_EVENT_STATE_READONLY;
 }
 
 void Element::NotifyStateChange(EventStates aStates) {
@@ -299,13 +299,26 @@ void Element::UpdateState(bool aNotify) {
 }  // namespace mozilla
 
 void nsIContent::UpdateEditableState(bool aNotify) {
-  nsIContent* parent = GetParent();
+  if (IsInNativeAnonymousSubtree()) {
+    // Don't propagate the editable flag into native anonymous subtrees.
+    if (IsRootOfNativeAnonymousSubtree()) {
+      return;
+    }
 
-  // Don't implicitly set the flag on the root of a native anonymous subtree.
-  // This needs to be set explicitly, see for example
-  // nsTextControlFrame::CreateRootNode().
-  SetEditableFlag(parent && parent->HasFlag(NODE_IS_EDITABLE) &&
-                  !IsRootOfNativeAnonymousSubtree());
+    // We allow setting the flag on NAC (explicitly, see
+    // nsTextControlFrame::CreateAnonymousContent for example), but not
+    // unsetting it.
+    //
+    // Otherwise, just the act of binding the NAC subtree into our non-anonymous
+    // parent would clear the flag, which is not good. As we shouldn't move NAC
+    // around, this is fine.
+    if (HasFlag(NODE_IS_EDITABLE)) {
+      return;
+    }
+  }
+
+  nsIContent* parent = GetParent();
+  SetEditableFlag(parent && parent->HasFlag(NODE_IS_EDITABLE));
 }
 
 namespace mozilla {
@@ -321,19 +334,28 @@ void Element::UpdateEditableState(bool aNotify) {
     // insertion into the document and UpdateState can be slow for
     // some kinds of elements even when not notifying.
     if (IsEditable()) {
-      RemoveStatesSilently(NS_EVENT_STATE_MOZ_READONLY);
-      AddStatesSilently(NS_EVENT_STATE_MOZ_READWRITE);
+      RemoveStatesSilently(NS_EVENT_STATE_READONLY);
+      AddStatesSilently(NS_EVENT_STATE_READWRITE);
     } else {
-      RemoveStatesSilently(NS_EVENT_STATE_MOZ_READWRITE);
-      AddStatesSilently(NS_EVENT_STATE_MOZ_READONLY);
+      RemoveStatesSilently(NS_EVENT_STATE_READWRITE);
+      AddStatesSilently(NS_EVENT_STATE_READONLY);
     }
   }
 }
 
-int32_t Element::TabIndex() {
-  const nsAttrValue* attrVal = mAttrs.GetAttr(nsGkAtoms::tabindex);
+Maybe<int32_t> Element::GetTabIndexAttrValue() {
+  const nsAttrValue* attrVal = GetParsedAttr(nsGkAtoms::tabindex);
   if (attrVal && attrVal->Type() == nsAttrValue::eInteger) {
-    return attrVal->GetIntegerValue();
+    return Some(attrVal->GetIntegerValue());
+  }
+
+  return Nothing();
+}
+
+int32_t Element::TabIndex() {
+  Maybe<int32_t> attrVal = GetTabIndexAttrValue();
+  if (attrVal.isSome()) {
+    return attrVal.value();
   }
 
   return TabIndexDefault();
@@ -341,21 +363,21 @@ int32_t Element::TabIndex() {
 
 void Element::Focus(const FocusOptions& aOptions, ErrorResult& aError) {
   nsFocusManager* fm = nsFocusManager::GetFocusManager();
+  if (!fm) {
+    return;
+  }
   // Also other browsers seem to have the hack to not re-focus (and flush) when
   // the element is already focused.
   // Until https://github.com/whatwg/html/issues/4512 is clarified, we'll
   // maintain interoperatibility by not re-focusing, independent of aOptions.
   // I.e., `focus({ preventScroll: true})` followed by `focus( { preventScroll:
   // false })` won't re-focus.
-  if (fm) {
-    if (fm->CanSkipFocus(this)) {
-      fm->NeedsFlushBeforeEventHandling(this);
-    } else {
-      aError = fm->SetFocus(
-          this, nsIFocusManager::FLAG_BYELEMENTFOCUS |
-                    nsFocusManager::FocusOptionsToFocusManagerFlags(aOptions));
-    }
+  if (fm->CanSkipFocus(this)) {
+    fm->NeedsFlushBeforeEventHandling(this);
+    return;
   }
+  aError = fm->SetFocus(
+      this, nsFocusManager::FocusOptionsToFocusManagerFlags(aOptions));
 }
 
 void Element::SetTabIndex(int32_t aTabIndex, mozilla::ErrorResult& aError) {
@@ -493,7 +515,7 @@ void Element::UnlockStyleStates(EventStates aStates) {
   locks->mLocks &= ~aStates;
 
   if (locks->mLocks.IsEmpty()) {
-    DeleteProperty(nsGkAtoms::lockedStyleStates);
+    RemoveProperty(nsGkAtoms::lockedStyleStates);
     ClearHasLockedStyleStates();
     delete locks;
   } else {
@@ -507,7 +529,7 @@ void Element::UnlockStyleStates(EventStates aStates) {
 void Element::ClearStyleStateLocks() {
   StyleStateLocks locks = LockedStyleStates();
 
-  DeleteProperty(nsGkAtoms::lockedStyleStates);
+  RemoveProperty(nsGkAtoms::lockedStyleStates);
   ClearHasLockedStyleStates();
 
   NotifyStyleStateChange(locks.mLocks);
@@ -967,7 +989,7 @@ nsRect Element::GetClientAreaRect() {
   // document, we have overlay scrollbars, and we aren't embedded in another
   // document
   bool overlayScrollbars =
-      LookAndFeel::GetInt(LookAndFeel::eIntID_UseOverlayScrollbars) != 0;
+      LookAndFeel::GetInt(LookAndFeel::IntID::UseOverlayScrollbars) != 0;
   bool rootContentDocument =
       presContext && presContext->IsRootContentDocument();
   if (overlayScrollbars && rootContentDocument &&
@@ -1218,8 +1240,9 @@ already_AddRefed<ShadowRoot> Element::AttachShadowWithoutNameChecks(
    *    context object's node document, host is context object,
    *    and mode is init's mode.
    */
+  auto* nim = nodeInfo->NodeInfoManager();
   RefPtr<ShadowRoot> shadowRoot =
-      new ShadowRoot(this, aMode, nodeInfo.forget());
+      new (nim) ShadowRoot(this, aMode, nodeInfo.forget());
 
   if (NodeOrAncestorHasDirAuto()) {
     shadowRoot->SetAncestorHasDirAuto();
@@ -1726,7 +1749,6 @@ nsresult Element::BindToTree(BindContext& aContext, nsINode& aParent) {
   // Now recurse into our kids. Ensure this happens after binding the shadow
   // root so that directionality of slots is updated.
   {
-    BindContext::NestingLevel level(aContext, *this);
     for (nsIContent* child = GetFirstChild(); child;
          child = child->GetNextSibling()) {
       rv = child->BindToTree(aContext, *this);
@@ -1911,14 +1933,14 @@ void Element::UnbindFromTree(bool aNullParent) {
   //
   // FIXME (Bug 522599): Need a test for this.
   if (MayHaveAnimations()) {
-    DeleteProperty(nsGkAtoms::transitionsOfBeforeProperty);
-    DeleteProperty(nsGkAtoms::transitionsOfAfterProperty);
-    DeleteProperty(nsGkAtoms::transitionsOfMarkerProperty);
-    DeleteProperty(nsGkAtoms::transitionsProperty);
-    DeleteProperty(nsGkAtoms::animationsOfBeforeProperty);
-    DeleteProperty(nsGkAtoms::animationsOfAfterProperty);
-    DeleteProperty(nsGkAtoms::animationsOfMarkerProperty);
-    DeleteProperty(nsGkAtoms::animationsProperty);
+    RemoveProperty(nsGkAtoms::transitionsOfBeforeProperty);
+    RemoveProperty(nsGkAtoms::transitionsOfAfterProperty);
+    RemoveProperty(nsGkAtoms::transitionsOfMarkerProperty);
+    RemoveProperty(nsGkAtoms::transitionsProperty);
+    RemoveProperty(nsGkAtoms::animationsOfBeforeProperty);
+    RemoveProperty(nsGkAtoms::animationsOfAfterProperty);
+    RemoveProperty(nsGkAtoms::animationsOfMarkerProperty);
+    RemoveProperty(nsGkAtoms::animationsProperty);
     if (document) {
       if (nsPresContext* presContext = document->GetPresContext()) {
         // We have to clear all pending restyle requests for the animations on
@@ -2050,9 +2072,7 @@ void Element::SetSMILOverrideStyleDeclaration(DeclarationBlock& aDeclaration) {
 
 bool Element::IsLabelable() const { return false; }
 
-bool Element::IsInteractiveHTMLContent(bool aIgnoreTabindex) const {
-  return false;
-}
+bool Element::IsInteractiveHTMLContent() const { return false; }
 
 DeclarationBlock* Element::GetInlineStyleDeclaration() const {
   if (!MayHaveStyle()) {
@@ -2613,8 +2633,7 @@ bool Element::ParseAttribute(int32_t aNamespaceID, nsAtom* aAttribute,
       return true;
     }
 
-    if (aAttribute == nsGkAtoms::exportparts &&
-        StaticPrefs::layout_css_shadow_parts_enabled()) {
+    if (aAttribute == nsGkAtoms::exportparts) {
       aResult.ParsePartMapping(aValue);
       return true;
     }
@@ -3325,8 +3344,78 @@ CORSMode Element::AttrValueToCORSMode(const nsAttrValue* aValue) {
   return CORSMode(aValue->GetEnumValue());
 }
 
+/**
+ * Returns nullptr if requests for fullscreen are allowed in the current
+ * context. Requests are only allowed if the user initiated them (like with
+ * a mouse-click or key press), unless this check has been disabled by
+ * setting the pref "full-screen-api.allow-trusted-requests-only" to false
+ * or if the caller is privileged. Feature policy may also deny requests.
+ * If fullscreen is not allowed, a key for the error message is returned.
+ */
 static const char* GetFullscreenError(CallerType aCallerType) {
-  return nsContentUtils::CheckRequestFullscreenAllowed(aCallerType);
+  // Privileged callers can always request fullscreen
+  if (aCallerType == CallerType::System) {
+    return nullptr;
+  }
+
+  // Ensure feature policy allows using the fullscreen API
+  /*if (!FeaturePolicyUtils::IsFeatureAllowed(aDocument,
+                                            NS_LITERAL_STRING("fullscreen"))) {
+    return "FullscreenDeniedFeaturePolicy";
+  }*/
+
+  // Bypass user interaction checks if preference is set
+  if (!StaticPrefs::full_screen_api_allow_trusted_requests_only()) {
+    return nullptr;
+  }
+
+  if (!UserActivation::IsHandlingUserInput()) {
+    return "FullscreenDeniedNotInputDriven";
+  }
+
+  // If more time has elapsed since the user input than is specified by the
+  // dom.event.handling-user-input-time-limit pref (default 1 second),
+  // disallow fullscreen
+  TimeDuration timeout = nsContentUtils::HandlingUserInputTimeout();
+  if (timeout > TimeDuration(nullptr) &&
+      (TimeStamp::Now() - UserActivation::GetHandlingInputStart()) > timeout) {
+    return "FullscreenDeniedNotInputDriven";
+  }
+
+  // Entering full-screen on mouse mouse event is only allowed with left mouse
+  // button
+  if (StaticPrefs::full_screen_api_mouse_event_allow_left_button_only() &&
+      (EventStateManager::sCurrentMouseBtn == MouseButton::eMiddle ||
+       EventStateManager::sCurrentMouseBtn == MouseButton::eRight)) {
+    return "FullscreenDeniedMouseEventOnlyLeftBtn";
+  }
+
+  return nullptr;
+}
+
+void Element::SetCapture(bool aRetargetToElement) {
+  // If there is already an active capture, ignore this request. This would
+  // occur if a splitter, frame resizer, etc had already captured and we don't
+  // want to override those.
+  if (!PresShell::GetCapturingContent()) {
+    PresShell::SetCapturingContent(
+        this, CaptureFlags::PreventDragStart |
+                  (aRetargetToElement ? CaptureFlags::RetargetToElement
+                                      : CaptureFlags::None));
+  }
+}
+
+void Element::SetCaptureAlways(bool aRetargetToElement) {
+  PresShell::SetCapturingContent(
+      this, CaptureFlags::PreventDragStart | CaptureFlags::IgnoreAllowedState |
+                (aRetargetToElement ? CaptureFlags::RetargetToElement
+                                    : CaptureFlags::None));
+}
+
+void Element::ReleaseCapture() {
+  if (PresShell::GetCapturingContent() == this) {
+    PresShell::ReleaseCapturingContent();
+  }
 }
 
 already_AddRefed<Promise> Element::RequestFullscreen(CallerType aCallerType,
@@ -3334,12 +3423,6 @@ already_AddRefed<Promise> Element::RequestFullscreen(CallerType aCallerType,
   auto request = FullscreenRequest::Create(this, aCallerType, aRv);
   RefPtr<Promise> promise = request->GetPromise();
 
-  if (!FeaturePolicyUtils::IsFeatureAllowed(OwnerDoc(),
-                                            NS_LITERAL_STRING("fullscreen"))) {
-    request->Reject("FullscreenDeniedFeaturePolicy");
-    return promise.forget();
-  }
-
   // Only grant fullscreen requests if this is called from inside a trusted
   // event handler (i.e. inside an event handler for a user initiated event).
   // This stops the fullscreen from being abused similar to the popups of old,
@@ -3360,12 +3443,11 @@ void Element::RequestPointerLock(CallerType aCallerType) {
 }
 
 already_AddRefed<Flex> Element::GetAsFlexContainer() {
-  nsIFrame* frame = GetPrimaryFrame();
-
   // We need the flex frame to compute additional info, and use
   // that annotated version of the frame.
   nsFlexContainerFrame* flexFrame =
-      nsFlexContainerFrame::GetFlexFrameWithComputedInfo(frame);
+      nsFlexContainerFrame::GetFlexFrameWithComputedInfo(
+          GetPrimaryFrame(FlushType::Layout));
 
   if (flexFrame) {
     RefPtr<Flex> flex = new Flex(this, flexFrame);
@@ -3376,7 +3458,8 @@ already_AddRefed<Flex> Element::GetAsFlexContainer() {
 
 void Element::GetGridFragments(nsTArray<RefPtr<Grid>>& aResult) {
   nsGridContainerFrame* frame =
-      nsGridContainerFrame::GetGridFrameWithComputedInfo(GetPrimaryFrame());
+      nsGridContainerFrame::GetGridFrameWithComputedInfo(
+          GetPrimaryFrame(FlushType::Layout));
 
   // If we get a nsGridContainerFrame from the prior call,
   // all the next-in-flow frames will also be nsGridContainerFrames.
@@ -3442,29 +3525,7 @@ already_AddRefed<Animation> Element::Animate(
     JSContext* aContext, JS::Handle<JSObject*> aKeyframes,
     const UnrestrictedDoubleOrKeyframeAnimationOptions& aOptions,
     ErrorResult& aError) {
-  Nullable<ElementOrCSSPseudoElement> target;
-  target.SetValue().SetAsElement() = this;
-  return Animate(target, aContext, aKeyframes, aOptions, aError);
-}
-
-/* static */
-already_AddRefed<Animation> Element::Animate(
-    const Nullable<ElementOrCSSPseudoElement>& aTarget, JSContext* aContext,
-    JS::Handle<JSObject*> aKeyframes,
-    const UnrestrictedDoubleOrKeyframeAnimationOptions& aOptions,
-    ErrorResult& aError) {
-  MOZ_ASSERT(!aTarget.IsNull() && (aTarget.Value().IsElement() ||
-                                   aTarget.Value().IsCSSPseudoElement()),
-             "aTarget should be initialized");
-
-  RefPtr<Element> referenceElement;
-  if (aTarget.Value().IsElement()) {
-    referenceElement = &aTarget.Value().GetAsElement();
-  } else {
-    referenceElement = aTarget.Value().GetAsCSSPseudoElement().Element();
-  }
-
-  nsCOMPtr<nsIGlobalObject> ownerGlobal = referenceElement->GetOwnerGlobal();
+  nsCOMPtr<nsIGlobalObject> ownerGlobal = GetOwnerGlobal();
   if (!ownerGlobal) {
     aError.Throw(NS_ERROR_FAILURE);
     return nullptr;
@@ -3476,8 +3537,8 @@ already_AddRefed<Animation> Element::Animate(
   // convention and needs to be called in caller's compartment.
   // This should match to RunConstructorInCallerCompartment attribute in
   // KeyframeEffect.webidl.
-  RefPtr<KeyframeEffect> effect = KeyframeEffect::Constructor(
-      global, aTarget, aKeyframes, aOptions, aError);
+  RefPtr<KeyframeEffect> effect =
+      KeyframeEffect::Constructor(global, this, aKeyframes, aOptions, aError);
   if (aError.Failed()) {
     return nullptr;
   }
@@ -3486,7 +3547,7 @@ already_AddRefed<Animation> Element::Animate(
   // needs to be called in the target element's realm.
   JSAutoRealm ar(aContext, global.Get());
 
-  AnimationTimeline* timeline = referenceElement->OwnerDoc()->Timeline();
+  AnimationTimeline* timeline = OwnerDoc()->Timeline();
   RefPtr<Animation> animation = Animation::Constructor(
       global, effect, Optional<AnimationTimeline*>(timeline), aError);
   if (aError.Failed()) {
@@ -3506,23 +3567,26 @@ already_AddRefed<Animation> Element::Animate(
 }
 
 void Element::GetAnimations(const GetAnimationsOptions& aOptions,
-                            nsTArray<RefPtr<Animation>>& aAnimations,
-                            Flush aFlush) {
-  if (aFlush == Flush::Yes) {
-    if (Document* doc = GetComposedDoc()) {
-      // We don't need to explicitly flush throttled animations here, since
-      // updating the animation style of elements will never affect the set of
-      // running animations and it's only the set of running animations that is
-      // important here.
-      //
-      // NOTE: Any changes to the flags passed to the following call should
-      // be reflected in the flags passed in DocumentOrShadowRoot::GetAnimations
-      // too.
-      doc->FlushPendingNotifications(
-          ChangesToFlush(FlushType::Style, false /* flush animations */));
-    }
+                            nsTArray<RefPtr<Animation>>& aAnimations) {
+  if (Document* doc = GetComposedDoc()) {
+    // We don't need to explicitly flush throttled animations here, since
+    // updating the animation style of elements will never affect the set of
+    // running animations and it's only the set of running animations that is
+    // important here.
+    //
+    // NOTE: Any changes to the flags passed to the following call should
+    // be reflected in the flags passed in DocumentOrShadowRoot::GetAnimations
+    // too.
+    doc->FlushPendingNotifications(
+        ChangesToFlush(FlushType::Style, false /* flush animations */));
   }
 
+  GetAnimationsWithoutFlush(aOptions, aAnimations);
+}
+
+void Element::GetAnimationsWithoutFlush(
+    const GetAnimationsOptions& aOptions,
+    nsTArray<RefPtr<Animation>>& aAnimations) {
   Element* elem = this;
   PseudoStyleType pseudoType = PseudoStyleType::NotPseudo;
   // For animations on generated-content elements, the animations are stored
@@ -3632,8 +3696,8 @@ void Element::SetOuterHTML(const nsAString& aOuterHTML, ErrorResult& aError) {
       localName = nsGkAtoms::body;
       namespaceID = kNameSpaceID_XHTML;
     }
-    RefPtr<DocumentFragment> fragment =
-        new DocumentFragment(OwnerDoc()->NodeInfoManager());
+    RefPtr<DocumentFragment> fragment = new (OwnerDoc()->NodeInfoManager())
+        DocumentFragment(OwnerDoc()->NodeInfoManager());
     nsContentUtils::ParseFragmentHTML(
         aOuterHTML, fragment, localName, namespaceID,
         OwnerDoc()->GetCompatibilityMode() == eCompatibility_NavQuirks, true);
@@ -3869,15 +3933,32 @@ float Element::FontSizeInflation() {
   return 1.0;
 }
 
-ReferrerPolicy Element::GetReferrerPolicyAsEnum() {
+void Element::GetImplementedPseudoElement(nsAString& aPseudo) const {
+  PseudoStyleType pseudoType = GetPseudoElementType();
+  if (pseudoType == PseudoStyleType::NotPseudo) {
+    return SetDOMStringToNull(aPseudo);
+  }
+  nsDependentAtomString pseudo(nsCSSPseudoElements::GetPseudoAtom(pseudoType));
+
+  // We want to use the modern syntax (::placeholder, etc), but the atoms only
+  // contain one semi-colon.
+  MOZ_ASSERT(pseudo.Length() > 2 && pseudo[0] == ':' && pseudo[1] != ':');
+
+  aPseudo.Truncate();
+  aPseudo.SetCapacity(pseudo.Length() + 1);
+  aPseudo.Append(':');
+  aPseudo.Append(pseudo);
+}
+
+ReferrerPolicy Element::GetReferrerPolicyAsEnum() const {
   if (IsHTMLElement()) {
-    const nsAttrValue* referrerValue = GetParsedAttr(nsGkAtoms::referrerpolicy);
-    return ReferrerPolicyFromAttr(referrerValue);
+    return ReferrerPolicyFromAttr(GetParsedAttr(nsGkAtoms::referrerpolicy));
   }
   return ReferrerPolicy::_empty;
 }
 
-ReferrerPolicy Element::ReferrerPolicyFromAttr(const nsAttrValue* aValue) {
+ReferrerPolicy Element::ReferrerPolicyFromAttr(
+    const nsAttrValue* aValue) const {
   if (aValue && aValue->Type() == nsAttrValue::eEnum) {
     return ReferrerPolicy(aValue->GetEnumValue());
   }
@@ -3952,14 +4033,14 @@ void Element::UnregisterIntersectionObserver(
   if (observers) {
     observers->Remove(aObserver);
     if (observers->IsEmpty()) {
-      DeleteProperty(nsGkAtoms::intersectionobserverlist);
+      RemoveProperty(nsGkAtoms::intersectionobserverlist);
     }
   }
 }
 
 void Element::UnlinkIntersectionObservers() {
   // IntersectionObserverPropertyDtor takes care of the hard work.
-  DeleteProperty(nsGkAtoms::intersectionobserverlist);
+  RemoveProperty(nsGkAtoms::intersectionobserverlist);
 }
 
 bool Element::UpdateIntersectionObservation(DOMIntersectionObserver* aObserver,

dom/base/Element.h

@@ -17,16 +17,15 @@
 #include "nsChangeHint.h"
 #include "nsContentUtils.h"
 #include "nsDOMAttributeMap.h"
+#include "nsStyleConsts.h"
 #include "nsINodeList.h"
 #include "nsIScrollableFrame.h"
-#include "nsPresContext.h"
 #include "Units.h"
 #include "mozilla/Attributes.h"
 #include "mozilla/CORSMode.h"
 #include "mozilla/EventForwards.h"
 #include "mozilla/EventStates.h"
 #include "mozilla/FlushType.h"
-#include "mozilla/PresShell.h"
 #include "mozilla/PseudoStyleType.h"
 #include "mozilla/RustCell.h"
 #include "mozilla/SMILAttr.h"
@@ -162,7 +161,7 @@ class Element : public FragmentOrElement {
 #ifdef MOZILLA_INTERNAL_API
   explicit Element(already_AddRefed<mozilla::dom::NodeInfo>&& aNodeInfo)
       : FragmentOrElement(std::move(aNodeInfo)),
-        mState(NS_EVENT_STATE_MOZ_READONLY | NS_EVENT_STATE_DEFINED) {
+        mState(NS_EVENT_STATE_READONLY | NS_EVENT_STATE_DEFINED) {
     MOZ_ASSERT(mNodeInfo->NodeType() == ELEMENT_NODE,
                "Bad NodeType in aNodeInfo");
     SetIsElement();
@@ -216,6 +215,11 @@ class Element : public FragmentOrElement {
    */
   int32_t TabIndex();
 
+  /**
+   * Get the parsed value of tabindex attribute.
+   */
+  Maybe<int32_t> GetTabIndexAttrValue();
+
   /**
    * Set tabIndex value to this element.
    */
@@ -378,7 +382,7 @@ class Element : public FragmentOrElement {
   /**
    * Returns if the element is interactive content as per HTML specification.
    */
-  virtual bool IsInteractiveHTMLContent(bool aIgnoreTabindex) const;
+  virtual bool IsInteractiveHTMLContent() const;
 
   /**
    * Returns |this| as an nsIMozBrowserFrame* if the element is a frame or
@@ -1180,31 +1184,11 @@ class Element : public FragmentOrElement {
     }
     return false;
   }
-  void SetCapture(bool aRetargetToElement) {
-    // If there is already an active capture, ignore this request. This would
-    // occur if a splitter, frame resizer, etc had already captured and we don't
-    // want to override those.
-    if (!PresShell::GetCapturingContent()) {
-      PresShell::SetCapturingContent(
-          this, CaptureFlags::PreventDragStart |
-                    (aRetargetToElement ? CaptureFlags::RetargetToElement
-                                        : CaptureFlags::None));
-    }
-  }
+  void SetCapture(bool aRetargetToElement);
 
-  void SetCaptureAlways(bool aRetargetToElement) {
-    PresShell::SetCapturingContent(
-        this, CaptureFlags::PreventDragStart |
-                  CaptureFlags::IgnoreAllowedState |
-                  (aRetargetToElement ? CaptureFlags::RetargetToElement
-                                      : CaptureFlags::None));
-  }
+  void SetCaptureAlways(bool aRetargetToElement);
 
-  void ReleaseCapture() {
-    if (PresShell::GetCapturingContent() == this) {
-      PresShell::ReleaseCapturingContent();
-    }
-  }
+  void ReleaseCapture();
 
   already_AddRefed<Promise> RequestFullscreen(CallerType, ErrorResult&);
   void RequestPointerLock(CallerType aCallerType);
@@ -1275,48 +1259,52 @@ class Element : public FragmentOrElement {
   MOZ_CAN_RUN_SCRIPT int32_t ScrollHeight();
   MOZ_CAN_RUN_SCRIPT void MozScrollSnap();
   MOZ_CAN_RUN_SCRIPT int32_t ClientTop() {
-    return nsPresContext::AppUnitsToIntCSSPixels(GetClientAreaRect().y);
+    return CSSPixel::FromAppUnits(GetClientAreaRect().y).Rounded();
   }
   MOZ_CAN_RUN_SCRIPT int32_t ClientLeft() {
-    return nsPresContext::AppUnitsToIntCSSPixels(GetClientAreaRect().x);
+    return CSSPixel::FromAppUnits(GetClientAreaRect().x).Rounded();
   }
   MOZ_CAN_RUN_SCRIPT int32_t ClientWidth() {
-    return nsPresContext::AppUnitsToIntCSSPixels(GetClientAreaRect().Width());
+    return CSSPixel::FromAppUnits(GetClientAreaRect().Width()).Rounded();
   }
   MOZ_CAN_RUN_SCRIPT int32_t ClientHeight() {
-    return nsPresContext::AppUnitsToIntCSSPixels(GetClientAreaRect().Height());
+    return CSSPixel::FromAppUnits(GetClientAreaRect().Height()).Rounded();
   }
   MOZ_CAN_RUN_SCRIPT int32_t ScrollTopMin() {
     nsIScrollableFrame* sf = GetScrollFrame();
-    return sf ? nsPresContext::AppUnitsToIntCSSPixels(sf->GetScrollRange().y)
-              : 0;
+    if (!sf) {
+      return 0;
+    }
+    return CSSPixel::FromAppUnits(sf->GetScrollRange().y).Rounded();
   }
   MOZ_CAN_RUN_SCRIPT int32_t ScrollTopMax() {
     nsIScrollableFrame* sf = GetScrollFrame();
-    return sf ? nsPresContext::AppUnitsToIntCSSPixels(
-                    sf->GetScrollRange().YMost())
-              : 0;
+    if (!sf) {
+      return 0;
+    }
+    return CSSPixel::FromAppUnits(sf->GetScrollRange().YMost()).Rounded();
   }
   MOZ_CAN_RUN_SCRIPT int32_t ScrollLeftMin() {
     nsIScrollableFrame* sf = GetScrollFrame();
-    return sf ? nsPresContext::AppUnitsToIntCSSPixels(sf->GetScrollRange().x)
-              : 0;
+    if (!sf) {
+      return 0;
+    }
+    return CSSPixel::FromAppUnits(sf->GetScrollRange().x).Rounded();
   }
   MOZ_CAN_RUN_SCRIPT int32_t ScrollLeftMax() {
     nsIScrollableFrame* sf = GetScrollFrame();
-    return sf ? nsPresContext::AppUnitsToIntCSSPixels(
-                    sf->GetScrollRange().XMost())
-              : 0;
+    if (!sf) {
+      return 0;
+    }
+    return CSSPixel::FromAppUnits(sf->GetScrollRange().XMost()).Rounded();
   }
 
   MOZ_CAN_RUN_SCRIPT double ClientHeightDouble() {
-    return nsPresContext::AppUnitsToDoubleCSSPixels(
-        GetClientAreaRect().Height());
+    return CSSPixel::FromAppUnits(GetClientAreaRect().Height());
   }
 
   MOZ_CAN_RUN_SCRIPT double ClientWidthDouble() {
-    return nsPresContext::AppUnitsToDoubleCSSPixels(
-        GetClientAreaRect().Width());
+    return CSSPixel::FromAppUnits(GetClientAreaRect().Width());
   }
 
   // This function will return the block size of first line box, no matter if
@@ -1337,20 +1325,12 @@ class Element : public FragmentOrElement {
       const UnrestrictedDoubleOrKeyframeAnimationOptions& aOptions,
       ErrorResult& aError);
 
-  // A helper method that factors out the common functionality needed by
-  // Element::Animate and CSSPseudoElement::Animate
-  static already_AddRefed<Animation> Animate(
-      const Nullable<ElementOrCSSPseudoElement>& aTarget, JSContext* aContext,
-      JS::Handle<JSObject*> aKeyframes,
-      const UnrestrictedDoubleOrKeyframeAnimationOptions& aOptions,
-      ErrorResult& aError);
-
-  enum class Flush { Yes, No };
-
   MOZ_CAN_RUN_SCRIPT
   void GetAnimations(const GetAnimationsOptions& aOptions,
-                     nsTArray<RefPtr<Animation>>& aAnimations,
-                     Flush aFlush = Flush::Yes);
+                     nsTArray<RefPtr<Animation>>& aAnimations);
+
+  void GetAnimationsWithoutFlush(const GetAnimationsOptions& aOptions,
+                                 nsTArray<RefPtr<Animation>>& aAnimations);
 
   static void GetAnimationsUnsorted(Element* aElement,
                                     PseudoStyleType aPseudoType,
@@ -1588,8 +1568,10 @@ class Element : public FragmentOrElement {
    */
   float FontSizeInflation();
 
-  ReferrerPolicy GetReferrerPolicyAsEnum();
-  ReferrerPolicy ReferrerPolicyFromAttr(const nsAttrValue* aValue);
+  void GetImplementedPseudoElement(nsAString&) const;
+
+  ReferrerPolicy GetReferrerPolicyAsEnum() const;
+  ReferrerPolicy ReferrerPolicyFromAttr(const nsAttrValue* aValue) const;
 
   /*
    * Helpers for .dataset.  This is implemented on Element, though only some
@@ -2039,6 +2021,11 @@ inline mozilla::dom::Element* nsINode::GetPreviousElementSibling() const {
   return nullptr;
 }
 
+inline mozilla::dom::Element* nsINode::GetAsElementOrParentElement() const {
+  return IsElement() ? const_cast<mozilla::dom::Element*>(AsElement())
+                     : GetParentElement();
+}
+
 inline mozilla::dom::Element* nsINode::GetNextElementSibling() const {
   nsIContent* nextSibling = GetNextSibling();
   while (nextSibling) {
@@ -2060,7 +2047,8 @@ inline mozilla::dom::Element* nsINode::GetNextElementSibling() const {
                                nsINode** aResult) const {           \
     *aResult = nullptr;                                             \
     RefPtr<mozilla::dom::NodeInfo> ni(aNodeInfo);                   \
-    RefPtr<_elementName> it = new _elementName(ni.forget());        \
+    auto* nim = ni->NodeInfoManager();                              \
+    RefPtr<_elementName> it = new (nim) _elementName(ni.forget());  \
     nsresult rv = const_cast<_elementName*>(this)->CopyInnerTo(it); \
     if (NS_SUCCEEDED(rv)) {                                         \
       it.forget(aResult);                                           \
@@ -2075,8 +2063,9 @@ inline mozilla::dom::Element* nsINode::GetNextElementSibling() const {
                                nsINode** aResult) const {                 \
     *aResult = nullptr;                                                   \
     RefPtr<mozilla::dom::NodeInfo> ni(aNodeInfo);                         \
+    auto* nim = ni->NodeInfoManager();                                    \
     RefPtr<_elementName> it =                                             \
-        new _elementName(ni.forget() EXPAND extra_args_);                 \
+        new (nim) _elementName(ni.forget() EXPAND extra_args_);           \
     nsresult rv = it->Init();                                             \
     nsresult rv2 = const_cast<_elementName*>(this)->CopyInnerTo(it);      \
     if (NS_FAILED(rv2)) {                                                 \

dom/base/EventSource.cpp

@@ -929,10 +929,9 @@ void EventSourceImpl::SetupHttpChannel() {
 nsresult EventSourceImpl::SetupReferrerInfo() {
   AssertIsOnMainThread();
   MOZ_ASSERT(!IsShutDown());
-  nsCOMPtr<Document> doc = mEventSource->GetDocumentIfCurrent();
-  if (doc) {
-    nsCOMPtr<nsIReferrerInfo> referrerInfo = new ReferrerInfo();
-    referrerInfo->InitWithDocument(doc);
+
+  if (nsCOMPtr<Document> doc = mEventSource->GetDocumentIfCurrent()) {
+    auto referrerInfo = MakeRefPtr<ReferrerInfo>(*doc);
     nsresult rv = mHttpChannel->SetReferrerInfoWithoutClone(referrerInfo);
     NS_ENSURE_SUCCESS(rv, rv);
   }
@@ -1781,7 +1780,7 @@ EventSource::EventSource(nsIGlobalObject* aGlobal,
   mImpl = new EventSourceImpl(this, aCookieSettings);
 }
 
-EventSource::~EventSource() {}
+EventSource::~EventSource() = default;
 
 nsresult EventSource::CreateAndDispatchSimpleEvent(const nsAString& aName) {
   RefPtr<Event> event = NS_NewDOMEvent(this, nullptr, nullptr);

dom/base/FilteredNodeIterator.h

@@ -0,0 +1,57 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * Implementation of a generic filtered iterator over nodes.
+ */
+
+#ifndef mozilla_dom_FilteredNodeIterator_h
+#define mozilla_dom_FilteredNodeIterator_h
+
+#include "nsINode.h"
+
+namespace mozilla {
+namespace dom {
+
+template <typename T, typename Iter>
+class FilteredNodeIterator : public Iter {
+ public:
+  explicit FilteredNodeIterator(const nsINode& aNode) : Iter(aNode) {
+    EnsureValid();
+  }
+
+  FilteredNodeIterator& begin() { return *this; }
+  using Iter::end;
+
+  void operator++() {
+    Iter::operator++();
+    EnsureValid();
+  }
+
+  using Iter::operator!=;
+
+  T* operator*() {
+    nsINode* node = Iter::operator*();
+    MOZ_ASSERT(!node || T::FromNode(node));
+    return static_cast<T*>(node);
+  }
+
+ private:
+  void EnsureValid() {
+    while (true) {
+      nsINode* node = Iter::operator*();
+      if (!node || T::FromNode(node)) {
+        return;
+      }
+      Iter::operator++();
+    }
+  }
+
+  FilteredNodeIterator() : Iter() {}
+};
+
+}  // namespace dom
+}  // namespace mozilla
+
+#endif  // mozilla_dom_FilteredNodeIterator.h

dom/base/FormData.cpp

@@ -15,14 +15,13 @@ using namespace mozilla;
 using namespace mozilla::dom;
 
 FormData::FormData(nsISupports* aOwner, NotNull<const Encoding*> aEncoding,
-                   Element* aOriginatingElement)
-    : HTMLFormSubmission(nullptr, EmptyString(), aEncoding,
-                         aOriginatingElement),
+                   Element* aSubmitter)
+    : HTMLFormSubmission(nullptr, EmptyString(), aEncoding, aSubmitter),
       mOwner(aOwner) {}
 
 FormData::FormData(const FormData& aFormData)
     : HTMLFormSubmission(aFormData.mActionURL, aFormData.mTarget,
-                         aFormData.mEncoding, aFormData.mOriginatingElement) {
+                         aFormData.mEncoding, aFormData.mSubmitter) {
   mOwner = aFormData.mOwner;
   mFormData = aFormData.mFormData;
 }

dom/base/FormData.h

@@ -25,7 +25,7 @@ class FormData final : public nsISupports,
                        public nsWrapperCache {
  private:
   FormData(const FormData& aFormData);
-  ~FormData() {}
+  ~FormData() = default;
 
   struct FormDataTuple {
     nsString name;
@@ -50,7 +50,7 @@ class FormData final : public nsISupports,
  public:
   explicit FormData(nsISupports* aOwner = nullptr,
                     NotNull<const Encoding*> aEncoding = UTF_8_ENCODING,
-                    Element* aOriginatingElement = nullptr);
+                    Element* aSubmitter = nullptr);
 
   already_AddRefed<FormData> Clone();
 

dom/base/FragmentOrElement.cpp

@@ -146,8 +146,11 @@ NS_INTERFACE_MAP_BEGIN(nsIContent)
 NS_INTERFACE_MAP_END
 
 NS_IMPL_MAIN_THREAD_ONLY_CYCLE_COLLECTING_ADDREF(nsIContent)
-NS_IMPL_MAIN_THREAD_ONLY_CYCLE_COLLECTING_RELEASE_WITH_LAST_RELEASE(
-    nsIContent, LastRelease())
+
+NS_IMPL_DOMARENA_DESTROY(nsIContent)
+
+NS_IMPL_MAIN_THREAD_ONLY_CYCLE_COLLECTING_RELEASE_WITH_LAST_RELEASE_AND_DESTROY(
+    nsIContent, LastRelease(), Destroy())
 
 nsIContent* nsIContent::FindFirstNonChromeOnlyAccessContent() const {
   // This handles also nested native anonymous content.
@@ -196,7 +199,7 @@ nsIContent::IMEState nsIContent::GetDesiredIMEState() {
     // Check for the special case where we're dealing with elements which don't
     // have the editable flag set, but are readwrite (such as text controls).
     if (!IsElement() ||
-        !AsElement()->State().HasState(NS_EVENT_STATE_MOZ_READWRITE)) {
+        !AsElement()->State().HasState(NS_EVENT_STATE_READWRITE)) {
       return IMEState(IMEState::DISABLED);
     }
   }
@@ -226,7 +229,7 @@ nsIContent::IMEState nsIContent::GetDesiredIMEState() {
   return state;
 }
 
-bool nsIContent::HasIndependentSelection() {
+bool nsIContent::HasIndependentSelection() const {
   nsIFrame* frame = GetPrimaryFrame();
   return (frame && frame->GetStateBits() & NS_FRAME_INDEPENDENT_SELECTION);
 }
@@ -279,22 +282,18 @@ nsresult nsIContent::LookupNamespaceURIInternal(
   }
   // Trace up the content parent chain looking for the namespace
   // declaration that declares aNamespacePrefix.
-  const nsIContent* content = this;
-  do {
-    if (content->IsElement() &&
-        content->AsElement()->GetAttr(kNameSpaceID_XMLNS, name, aNamespaceURI))
+  for (Element* element = GetAsElementOrParentElement(); element;
+       element = element->GetParentElement()) {
+    if (element->GetAttr(kNameSpaceID_XMLNS, name, aNamespaceURI)) {
       return NS_OK;
-  } while ((content = content->GetParent()));
+    }
+  }
   return NS_ERROR_FAILURE;
 }
 
 nsAtom* nsIContent::GetLang() const {
-  for (const auto* content = this; content; content = content->GetParent()) {
-    if (!content->IsElement()) {
-      continue;
-    }
-
-    auto* element = content->AsElement();
+  for (const Element* element = GetAsElementOrParentElement(); element;
+       element = element->GetParentElement()) {
     if (!element->GetAttrCount()) {
       continue;
     }
@@ -1325,14 +1324,14 @@ NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(FragmentOrElement)
       nsStaticAtom* const* props =
           Element::HTMLSVGPropertiesToTraverseAndUnlink();
       for (uint32_t i = 0; props[i]; ++i) {
-        tmp->DeleteProperty(props[i]);
+        tmp->RemoveProperty(props[i]);
       }
     }
 
     if (tmp->MayHaveAnimations()) {
       nsAtom** effectProps = EffectSet::GetEffectSetPropertyAtoms();
       for (uint32_t i = 0; effectProps[i]; ++i) {
-        tmp->DeleteProperty(effectProps[i]);
+        tmp->RemoveProperty(effectProps[i]);
       }
     }
   }
@@ -1794,12 +1793,8 @@ NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INTERNAL(FragmentOrElement)
       orphan.AppendLiteral(" (orphan)");
     }
 
-    static const char* kNSURIs[] = {" ([none])", " (xmlns)",  " (xml)",
-                                    " (xhtml)",  " (XLink)",  " (XSLT)",
-                                    " (XBL)",    " (MathML)", " (RDF)",
-                                    " (XUL)",    " (SVG)",    " (XML Events)"};
-    const char* nsuri = nsid < ArrayLength(kNSURIs) ? kNSURIs[nsid] : "";
-    SprintfLiteral(name, "FragmentOrElement%s %s%s%s%s %s", nsuri,
+    const char* nsuri = nsNameSpaceManager::GetNameSpaceDisplayName(nsid);
+    SprintfLiteral(name, "FragmentOrElement %s %s%s%s%s %s", nsuri,
                    localName.get(), NS_ConvertUTF16toUTF8(id).get(),
                    NS_ConvertUTF16toUTF8(classes).get(), orphan.get(),
                    uri.get());
@@ -2048,16 +2043,17 @@ void FragmentOrElement::SetInnerHTMLInternal(const nsAString& aInnerHTML,
 
   nsAutoScriptLoaderDisabler sld(doc);
 
-  nsAtom* contextLocalName = NodeInfo()->NameAtom();
-  int32_t contextNameSpaceID = GetNameSpaceID();
-
+  FragmentOrElement* parseContext = this;
   if (ShadowRoot* shadowRoot = ShadowRoot::FromNode(this)) {
-    // Fix up the context to be the host of the ShadowRoot.
-    contextLocalName = shadowRoot->GetHost()->NodeInfo()->NameAtom();
-    contextNameSpaceID = shadowRoot->GetHost()->GetNameSpaceID();
+    // Fix up the context to be the host of the ShadowRoot.  See
+    // https://w3c.github.io/DOM-Parsing/#dom-innerhtml-innerhtml setter step 1.
+    parseContext = shadowRoot->GetHost();
   }
 
   if (doc->IsHTMLDocument()) {
+    nsAtom* contextLocalName = parseContext->NodeInfo()->NameAtom();
+    int32_t contextNameSpaceID = parseContext->GetNameSpaceID();
+
     int32_t oldChildCount = target->GetChildCount();
     aError = nsContentUtils::ParseFragmentHTML(
         aInnerHTML, target, contextLocalName, contextNameSpaceID,
@@ -2068,14 +2064,14 @@ void FragmentOrElement::SetInnerHTMLInternal(const nsAString& aInnerHTML,
                                                        oldChildCount);
   } else {
     RefPtr<DocumentFragment> df = nsContentUtils::CreateContextualFragment(
-        target, aInnerHTML, true, aError);
+        parseContext, aInnerHTML, true, aError);
     if (!aError.Failed()) {
       // Suppress assertion about node removal mutation events that can't have
       // listeners anyway, because no one has had the chance to register
       // mutation listeners on the fragment that comes from the parser.
       nsAutoScriptBlockerSuppressNodeRemoved scriptBlocker;
 
-      static_cast<nsINode*>(target)->AppendChild(*df, aError);
+      target->AppendChild(*df, aError);
       mb.NodesAdded();
     }
   }

dom/base/FragmentOrElement.h

@@ -55,7 +55,7 @@ class nsNodeSupportsWeakRefTearoff final : public nsISupportsWeakReference {
   NS_DECL_CYCLE_COLLECTION_CLASS(nsNodeSupportsWeakRefTearoff)
 
  private:
-  ~nsNodeSupportsWeakRefTearoff() {}
+  ~nsNodeSupportsWeakRefTearoff() = default;
 
   nsCOMPtr<nsINode> mNode;
 };

dom/base/FullscreenChange.h

@@ -39,12 +39,16 @@ class FullscreenChange : public LinkedListElement<FullscreenChange> {
     }
   }
 
-  void MayRejectPromise() const {
+  void MayRejectPromise(const nsACString& aMessage) {
     if (mPromise) {
       MOZ_ASSERT(mPromise->State() == Promise::PromiseState::Pending);
-      mPromise->MaybeReject(NS_ERROR_DOM_TYPE_ERR);
+      mPromise->MaybeRejectWithTypeError(aMessage);
     }
   }
+  template <int N>
+  void MayRejectPromise(const char (&aMessage)[N]) {
+    MayRejectPromise(nsLiteralCString(aMessage));
+  }
 
  protected:
   typedef dom::Promise Promise;
@@ -89,14 +93,14 @@ class FullscreenRequest : public FullscreenChange {
 
   // Reject the fullscreen request with the given reason.
   // It will dispatch the fullscreenerror event.
-  void Reject(const char* aReason) const {
+  void Reject(const char* aReason) {
     if (nsPresContext* presContext = Document()->GetPresContext()) {
       auto pendingEvent = MakeUnique<PendingFullscreenEvent>(
           FullscreenEventType::Error, Document(), mElement);
       presContext->RefreshDriver()->ScheduleFullscreenEvent(
           std::move(pendingEvent));
     }
-    MayRejectPromise();
+    MayRejectPromise("Fullscreen request denied");
     nsContentUtils::ReportToConsole(nsIScriptError::warningFlag,
                                     NS_LITERAL_CSTRING("DOM"), Document(),
                                     nsContentUtils::eDOM_PROPERTIES, aReason);
@@ -143,7 +147,7 @@ class FullscreenExit : public FullscreenChange {
     return WrapUnique(new FullscreenExit(aDoc, nullptr));
   }
 
-  ~FullscreenExit() { MOZ_COUNT_DTOR(FullscreenExit); }
+  MOZ_COUNTED_DTOR(FullscreenExit)
 
  private:
   FullscreenExit(dom::Document* aDoc, already_AddRefed<Promise> aPromise)