diff --git a/js/public/Transcoding.h b/js/public/Transcoding.h
index ef38ae256a..efbef01455 100644
--- a/js/public/Transcoding.h
+++ b/js/public/Transcoding.h
@@ -19,7 +19,6 @@
 #include "js/RootingAPI.h"  // JS::Handle, JS::MutableHandle
 
 struct JS_PUBLIC_API JSContext;
-class JS_PUBLIC_API JSFunction;
 class JS_PUBLIC_API JSObject;
 class JS_PUBLIC_API JSScript;
 
@@ -102,9 +101,6 @@ extern JS_PUBLIC_API TranscodeResult EncodeScript(JSContext* cx,
                                                   TranscodeBuffer& buffer,
                                                   Handle<JSScript*> script);
 
-extern JS_PUBLIC_API TranscodeResult EncodeInterpretedFunction(
-    JSContext* cx, TranscodeBuffer& buffer, Handle<JSObject*> funobj);
-
 // Decode JSScript from the buffer.
 //
 // The start of `buffer` and `cursorIndex` should meet
@@ -124,11 +120,6 @@ extern JS_PUBLIC_API TranscodeResult
 DecodeScript(JSContext* cx, const ReadOnlyCompileOptions& options,
              const TranscodeRange& range, MutableHandle<JSScript*> scriptp);
 
-extern JS_PUBLIC_API TranscodeResult DecodeInterpretedFunction(
-    JSContext* cx, const ReadOnlyCompileOptions& options,
-    TranscodeBuffer& buffer, MutableHandle<JSFunction*> funp,
-    size_t cursorIndex = 0);
-
 // If js::UseOffThreadParseGlobal is true, decode JSScript from the buffer.
 //
 // If js::UseOffThreadParseGlobal is false, decode CompilationStencil from the
diff --git a/js/public/friend/ErrorNumbers.msg b/js/public/friend/ErrorNumbers.msg
index 801385cb80..2dcd5c315c 100644
--- a/js/public/friend/ErrorNumbers.msg
+++ b/js/public/friend/ErrorNumbers.msg
@@ -183,7 +183,6 @@ MSG_DEF(JSMSG_OBJECT_ACCESS_DENIED,    0, JSEXN_ERR, "Permission denied to acces
 MSG_DEF(JSMSG_PROPERTY_ACCESS_DENIED,  1, JSEXN_ERR, "Permission denied to access property {0}")
 
 // JSAPI-only (Not thrown as JS exceptions)
-MSG_DEF(JSMSG_BAD_CLONE_FUNOBJ_SCOPE,  0, JSEXN_TYPEERR, "bad cloned function scope chain")
 MSG_DEF(JSMSG_CANT_CLONE_OBJECT,       0, JSEXN_TYPEERR, "can't clone object")
 MSG_DEF(JSMSG_CANT_OPEN,               2, JSEXN_ERR, "can't open {0}: {1}")
 MSG_DEF(JSMSG_SUPPORT_NOT_ENABLED,     1, JSEXN_ERR, "support for {0} is not enabled")
diff --git a/js/src/builtin/TestingFunctions.cpp b/js/src/builtin/TestingFunctions.cpp
index e8f42b06c3..fc8c0efc24 100644
--- a/js/src/builtin/TestingFunctions.cpp
+++ b/js/src/builtin/TestingFunctions.cpp
@@ -4724,7 +4724,6 @@ static bool ShellCloneAndExecuteScript(JSContext* cx, unsigned argc,
 
   JS::CompileOptions options(cx);
   options.setFileAndLine(filename.get(), lineno);
-  options.setNoScriptRval(true);
 
   JS::SourceText<char16_t> srcBuf;
   if (!srcBuf.init(cx, src, srclen, SourceOwnership::Borrowed)) {
@@ -4746,14 +4745,19 @@ static bool ShellCloneAndExecuteScript(JSContext* cx, unsigned argc,
     return false;
   }
 
-  AutoRealm ar(cx, global);
-
   JS::RootedValue rval(cx);
-  if (!JS::CloneAndExecuteScript(cx, script, &rval)) {
+  {
+    AutoRealm ar(cx, global);
+    if (!JS::CloneAndExecuteScript(cx, script, &rval)) {
+      return false;
+    }
+  }
+
+  if (!cx->compartment()->wrap(cx, &rval)) {
     return false;
   }
 
-  args.rval().setUndefined();
+  args.rval().set(rval);
   return true;
 }
 
diff --git a/js/src/jit-test/tests/asm.js/bug1542130.js b/js/src/jit-test/tests/asm.js/bug1542130.js
index bab11b8de3..9b809bab69 100644
--- a/js/src/jit-test/tests/asm.js/bug1542130.js
+++ b/js/src/jit-test/tests/asm.js/bug1542130.js
@@ -1,6 +1,6 @@
 // |jit-test| error:AsmJS modules do not yet support cloning; skip-if: !isAsmJSCompilationAvailable()
 var g = newGlobal();
-g.evaluate(`
+cloneAndExecuteScript(`
   function h() {
     function f() {
       'use asm';
@@ -9,6 +9,4 @@ g.evaluate(`
     }
     return f;
   }
-`);
-var h = clone(g.h);
-h();
+`, g);
diff --git a/js/src/jit-test/tests/asm.js/testBug893519.js b/js/src/jit-test/tests/asm.js/testBug893519.js
index 3b747fa6ad..cf801f62b0 100644
--- a/js/src/jit-test/tests/asm.js/testBug893519.js
+++ b/js/src/jit-test/tests/asm.js/testBug893519.js
@@ -1,6 +1,4 @@
-// |jit-test| error:Error; skip-if: !isAsmJSCompilationAvailable()
+// |jit-test| error:Error: AsmJS modules do not yet support cloning; skip-if: !isAsmJSCompilationAvailable()
 
 var g = newGlobal({newCompartment: true});
-evaluate("function h() { function f() { 'use asm'; function g() { return 42 } return g } return f }", { global:g});
-var h = clone(g.h);
-assertEq(h()()(), 42);
+cloneAndExecuteScript("function h() { function f() { 'use asm'; function g() { return 42 } return g } return f }", g);
diff --git a/js/src/jit-test/tests/auto-regress/bug1466626-2.js b/js/src/jit-test/tests/auto-regress/bug1466626-2.js
index 62247171e2..056ea075e2 100644
--- a/js/src/jit-test/tests/auto-regress/bug1466626-2.js
+++ b/js/src/jit-test/tests/auto-regress/bug1466626-2.js
@@ -3,16 +3,12 @@
 var globals = [];
 for (var i = 0; i < 24; ++i) {
     var g = newGlobal();
-    g.eval(`
-        function f(){}
-        var env = {};
-    `);
     globals.push(g);
 }
 
 var i = 0;
 oomTest(function() {
     globals[(i++) % globals.length].eval(`
-        this.clone(this.f, this.env);
+        evaluate("function f() {}", {envChainObject: this.env});
     `);
 });
diff --git a/js/src/jit-test/tests/auto-regress/bug677977.js b/js/src/jit-test/tests/auto-regress/bug677977.js
index c4211e5ccb..e2b0735613 100644
--- a/js/src/jit-test/tests/auto-regress/bug677977.js
+++ b/js/src/jit-test/tests/auto-regress/bug677977.js
@@ -23,4 +23,3 @@ this.gczeal(hits, 2);
 var fn = g.evaluate("(function (a) { return 5 + a; })");
 var g2 = newGlobal({newCompartment: true});
 dbg.addDebuggee(g2, dbg);
-g2.clone(fn);
diff --git a/js/src/jit-test/tests/basic/bug1106982-2.js b/js/src/jit-test/tests/basic/bug1106982-2.js
index 378d10f514..1983c4b04f 100644
--- a/js/src/jit-test/tests/basic/bug1106982-2.js
+++ b/js/src/jit-test/tests/basic/bug1106982-2.js
@@ -10,11 +10,6 @@ var p = new Proxy(t, {
     },
     get(t, id) { return t[id]; }
 });
-evaluate(`function testFunc() {
-    x += " x";
-}`);
-
-var cloneFunc = clone(testFunc, p);
-cloneFunc();
+evaluate(`x += " x";`, {envChainObject: p});
 assertEq(hits, 2);
 assertEq(t.x, "undefined x");
diff --git a/js/src/jit-test/tests/basic/bug1405820.js b/js/src/jit-test/tests/basic/bug1405820.js
deleted file mode 100644
index 58594d77a5..0000000000
--- a/js/src/jit-test/tests/basic/bug1405820.js
+++ /dev/null
@@ -1,5 +0,0 @@
-// |jit-test| error: Error
-
-var g = newGlobal();
-g.f = setJitCompilerOption;
-g.eval("clone(f)()(9)")
diff --git a/js/src/jit-test/tests/basic/bug1412654.js b/js/src/jit-test/tests/basic/bug1412654.js
deleted file mode 100644
index d3b96a73ad..0000000000
--- a/js/src/jit-test/tests/basic/bug1412654.js
+++ /dev/null
@@ -1,4 +0,0 @@
-// |jit-test| error: can't clone
-var gv = newGlobal();
-gv.f = (class get {});
-gv.eval('f = clone(f);');
diff --git a/js/src/jit-test/tests/basic/bug751139.js b/js/src/jit-test/tests/basic/bug751139.js
deleted file mode 100644
index a889ab6239..0000000000
--- a/js/src/jit-test/tests/basic/bug751139.js
+++ /dev/null
@@ -1,7 +0,0 @@
-
-load(libdir + "asserts.js");
-
-function C(a, b) {}
-var f = C.bind(null, 2);
-var that = this;
-assertThrowsInstanceOf(function () { g = clone(f, that)}, TypeError);
diff --git a/js/src/jit-test/tests/basic/function-cloning-1.js b/js/src/jit-test/tests/basic/function-cloning-1.js
deleted file mode 100644
index 92511b15bd..0000000000
--- a/js/src/jit-test/tests/basic/function-cloning-1.js
+++ /dev/null
@@ -1,4 +0,0 @@
-var g = newGlobal();
-var f1 = g.evaluate("(function (x) { function inner() {}; })");
-gczeal(2, 1); // Exercise all the edge cases in cloning, please.
-var f2 = clone(f1);
diff --git a/js/src/jit-test/tests/basic/testLet.js b/js/src/jit-test/tests/basic/testLet.js
index 9ffc062b0a..4edec77ce7 100644
--- a/js/src/jit-test/tests/basic/testLet.js
+++ b/js/src/jit-test/tests/basic/testLet.js
@@ -19,9 +19,9 @@ function test(str, arg, result)
     // test reflection logic
     Reflect.parse(got);
 
-    // test xdr by cloning a cross-compartment function
+    // test script cloning
     var code = "(function (x) { " + str + " })";
-    var c = clone(otherGlobal.evaluate(code));
+    var c = cloneAndExecuteScript(code, otherGlobal);
     assertEq(c.toString(), eval(code).toString());
 
     var got = fun(arg);
diff --git a/js/src/jit-test/tests/basic/testScriptCloning.js b/js/src/jit-test/tests/basic/testScriptCloning.js
index 4099acfb96..2d9eaccd49 100644
--- a/js/src/jit-test/tests/basic/testScriptCloning.js
+++ b/js/src/jit-test/tests/basic/testScriptCloning.js
@@ -1,21 +1,22 @@
 var g = newGlobal();
 
-g.f = new Function('return function(x) { return x };');
-assertEq(g.eval("clone(f)()(9)"), 9);
+var f;
+f = cloneAndExecuteScript('(function(x) { return x })', g);
+assertEq(f(9), 9);
 
-g.f = new Function('return function(x) { { let y = x+1; return y } };');
-assertEq(g.eval("clone(f)()(9)"), 10);
+f = cloneAndExecuteScript('(function(x) { { let y = x+1; return y } })', g);
+assertEq(f(9), 10);
 
-g.f = new Function('return function(x) { { let y = x, z = 1; return y+z } };');
-assertEq(g.eval("clone(f)()(9)"), 10);
+f = cloneAndExecuteScript('(function(x) { { let y = x, z = 1; return y+z } })', g);
+assertEq(f(9), 10);
 
-g.f = new Function('return function(x) { return x.search(/ponies/) };');
-assertEq(g.eval("clone(f)()('123ponies')"), 3);
+f = cloneAndExecuteScript('(function(x) { return x.search(/ponies/) })', g);
+assertEq(f('123ponies'), 3);
 
-g.f = new Function('return function(x,y) { return x.search(/a/) + y.search(/b/) };');
-assertEq(g.eval("clone(f)()('12a','foo')"), 1);
+f = cloneAndExecuteScript('(function(x, y) { return x.search(/a/) + y.search(/b/) })', g);
+assertEq(f('12a','foo'), 1);
 
-g.f = new Function('return function(x) { switch(x) { case "a": return "b"; case null: return "c" } };');
-assertEq(g.eval("clone(f)()('a')"), "b");
-assertEq(g.eval("clone(f)()(null)"), "c");
-assertEq(g.eval("clone(f)()(3)"), undefined);
+f = cloneAndExecuteScript('(function(x) { switch(x) { case "a": return "b"; case null: return "c" } })', g);
+assertEq(f('a'), "b");
+assertEq(f(null), "c");
+assertEq(f(3), undefined);
diff --git a/js/src/jit-test/tests/basic/weird-scopechains.js b/js/src/jit-test/tests/basic/weird-scopechains.js
index 035a934ec5..c992f315bb 100644
--- a/js/src/jit-test/tests/basic/weird-scopechains.js
+++ b/js/src/jit-test/tests/basic/weird-scopechains.js
@@ -6,20 +6,6 @@ function assertWithMessage(got, expected, message) {
     assertEq(message + ": " + got, message + ": " + expected);
 }
 
-function testFunc() {
-    assertWithMessage(checkNameLookup(), "local", "nameLookup");
-    assertWithMessage(checkThisBinding(), "local", "thisBinding");
-
-    // Important: lambda needs to close over "reason", so it won't just get the
-    // scope of testFunc as its scope.  Instead it'll get the Call object
-    // "reason" lives in.
-    var reason = " in lambda in Call";
-    (function() {
-	assertWithMessage(checkNameLookup(), "local", "nameLookup" + reason);
-	assertWithMessage(checkThisBinding(), "local", "thisBinding" + reason);
-    })();
-}
-
 var obj = {
     checkNameLookup: function() {
 	return "local";
@@ -30,5 +16,16 @@ var obj = {
     },
 };
 
-var cloneFunc = clone(testFunc, obj);
-cloneFunc();
+evaluate("(" + function() {
+    assertWithMessage(checkNameLookup(), "local", "nameLookup");
+    assertWithMessage(checkThisBinding(), "local", "thisBinding");
+
+    // Important: lambda needs to close over "reason", so it won't just get the
+    // scope of testFunc as its scope.  Instead it'll get the Call object
+    // "reason" lives in.
+    var reason = " in lambda in Call";
+    (function() {
+	assertWithMessage(checkNameLookup(), "local", "nameLookup" + reason);
+	assertWithMessage(checkThisBinding(), "local", "thisBinding" + reason);
+    })();
+} + ")()", {envChainObject: obj});
diff --git a/js/src/jit-test/tests/binast/lazy/auto-regress/bug677977.binjs b/js/src/jit-test/tests/binast/lazy/auto-regress/bug677977.binjs
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deleted file mode 100644
index a61c650f5c..0000000000
--- a/js/src/jit-test/tests/binast/lazy/basic/bug1405820.dir
+++ /dev/null
@@ -1 +0,0 @@
-// |jit-test| error: Error
diff --git a/js/src/jit-test/tests/binast/lazy/basic/bug751139.binjs b/js/src/jit-test/tests/binast/lazy/basic/bug751139.binjs
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deleted file mode 100644
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diff --git a/js/src/jit-test/tests/binast/lazy/gc/bug-1161968.binjs b/js/src/jit-test/tests/binast/lazy/gc/bug-1161968.binjs
deleted file mode 100644
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deleted file mode 100644
index 922d49f22e..0000000000
--- a/js/src/jit-test/tests/binast/lazy/gc/bug-1161968.dir
+++ /dev/null
@@ -1 +0,0 @@
-// |jit-test| skip-if: !('gczeal' in this)
diff --git a/js/src/jit-test/tests/binast/nonlazy/auto-regress/bug677977.binjs b/js/src/jit-test/tests/binast/nonlazy/auto-regress/bug677977.binjs
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deleted file mode 100644
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deleted file mode 100644
index a61c650f5c..0000000000
--- a/js/src/jit-test/tests/binast/nonlazy/basic/bug1405820.dir
+++ /dev/null
@@ -1 +0,0 @@
-// |jit-test| error: Error
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index c5710f8e08..0000000000
Binary files a/js/src/jit-test/tests/binast/nonlazy/debug/onNewScript-02.binjs and /dev/null differ
diff --git a/js/src/jit-test/tests/binast/nonlazy/gc/bug-1161968.binjs b/js/src/jit-test/tests/binast/nonlazy/gc/bug-1161968.binjs
deleted file mode 100644
index cd13375686..0000000000
Binary files a/js/src/jit-test/tests/binast/nonlazy/gc/bug-1161968.binjs and /dev/null differ
diff --git a/js/src/jit-test/tests/binast/nonlazy/gc/bug-1161968.dir b/js/src/jit-test/tests/binast/nonlazy/gc/bug-1161968.dir
deleted file mode 100644
index 922d49f22e..0000000000
--- a/js/src/jit-test/tests/binast/nonlazy/gc/bug-1161968.dir
+++ /dev/null
@@ -1 +0,0 @@
-// |jit-test| skip-if: !('gczeal' in this)
diff --git a/js/src/jit-test/tests/debug/Source-invisible.js b/js/src/jit-test/tests/debug/Source-invisible.js
index 9778f13f03..420b6faec8 100644
--- a/js/src/jit-test/tests/debug/Source-invisible.js
+++ b/js/src/jit-test/tests/debug/Source-invisible.js
@@ -1,11 +1,9 @@
 // Looking at ScriptSourceObjects in invisible-to-debugger compartments is okay.
 
 var gi = newGlobal({ newCompartment: true, invisibleToDebugger: true });
-gi.eval('function f() {}');
 
 var gv = newGlobal({newCompartment: true});
-gv.f = gi.f;
-gv.eval('f = clone(f);');
+gi.cloneAndExecuteScript('function f() {}', gv);
 
 var dbg = new Debugger;
 var gvw = dbg.addDebuggee(gv);
diff --git a/js/src/jit-test/tests/debug/bug1406437.js b/js/src/jit-test/tests/debug/bug1406437.js
index 16ead98ba2..4085f80a2d 100644
--- a/js/src/jit-test/tests/debug/bug1406437.js
+++ b/js/src/jit-test/tests/debug/bug1406437.js
@@ -1,6 +1,5 @@
 var g = newGlobal({newCompartment: true});
-g.f = function() {};
-g.eval('f = clone(f);');
+cloneAndExecuteScript('function f() {}', g);
 var dbg = new Debugger;
 var dg = dbg.addDebuggee(g);
 dg.getOwnPropertyDescriptor('f').value.script.source;
diff --git a/js/src/jit-test/tests/debug/onNewScript-01.js b/js/src/jit-test/tests/debug/onNewScript-01.js
index 6d48d09f74..7c820ae58b 100644
--- a/js/src/jit-test/tests/debug/onNewScript-01.js
+++ b/js/src/jit-test/tests/debug/onNewScript-01.js
@@ -37,9 +37,8 @@ assertEq(fn(8), 13);
 assertEq(hits, 1);
 
 // cloning functions across compartments
-fn = g.evaluate("(function(a) { return 5 + a; })");
 var g2 = newGlobal({newCompartment: true});
 dbg.addDebuggee(g2, dbg);
 hits = 0;
-g2.clone(fn);
+cloneAndExecuteScript("(function(a) { return 5 + a; })", g2);
 assertEq(hits, 1);
diff --git a/js/src/jit-test/tests/debug/onNewScript-02.js b/js/src/jit-test/tests/debug/onNewScript-02.js
index a050da374b..1f284c48c3 100644
--- a/js/src/jit-test/tests/debug/onNewScript-02.js
+++ b/js/src/jit-test/tests/debug/onNewScript-02.js
@@ -44,7 +44,7 @@ test(function () { g.eval("var obj = {get x() { return 1; }, set x(v) { print(v)
 test(function () { return g.Function("a", "b", "return b - a;"); });
 
 // cloning a function with nested functions
-test(function () { g.clone(evaluate("(function(x) { return x + 1; })")); });
+test(function () { cloneAndExecuteScript("(function(x) { return x + 1; })", g); });
 
 // eval declaring a star generator
 test(function () { g.eval("function* sg(n) { for (var i=0;i<n;i++) yield i; }"); });
diff --git a/js/src/jit-test/tests/gc/bug-1161968.js b/js/src/jit-test/tests/gc/bug-1161968.js
index 68313ea96d..1cee3eca76 100644
--- a/js/src/jit-test/tests/gc/bug-1161968.js
+++ b/js/src/jit-test/tests/gc/bug-1161968.js
@@ -5,10 +5,8 @@
 gczeal(2,21);
 
 var gi = newGlobal();
-gi.eval('function f() {}');
 
 var gv = newGlobal();
-gv.f = gi.f;
-gv.eval('f = clone(f);');
+gi.cloneAndExecuteScript('function f() {}', gv);
 
 var dbg = new Debugger;
diff --git a/js/src/jsapi-tests/moz.build b/js/src/jsapi-tests/moz.build
index 47d8529904..686a1e882d 100644
--- a/js/src/jsapi-tests/moz.build
+++ b/js/src/jsapi-tests/moz.build
@@ -22,7 +22,6 @@ UNIFIED_SOURCES += [
     "testCallArgs.cpp",
     "testCallNonGenericMethodOnProxy.cpp",
     "testChromeBuffer.cpp",
-    "testCloneScript.cpp",
     "testCompileNonSyntactic.cpp",
     "testCompileUtf8.cpp",
     "testDateToLocaleString.cpp",
diff --git a/js/src/jsapi-tests/testCloneScript.cpp b/js/src/jsapi-tests/testCloneScript.cpp
deleted file mode 100644
index d4a4344068..0000000000
--- a/js/src/jsapi-tests/testCloneScript.cpp
+++ /dev/null
@@ -1,157 +0,0 @@
-/* Test script cloning.
- */
-/* 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 "mozilla/Utf8.h"  // mozilla::Utf8Unit
-
-#include <string.h>  // strlen
-
-#include "jsapi.h"  // sundry symbols not moved to more-specific headers yet
-#include "jsfriendapi.h"
-#include "jspubtd.h"  // JS::RootedObjectVector
-
-#include "js/CompilationAndEvaluation.h"  // JS::CompileFunction
-#include "js/CompileOptions.h"            // JS::CompileOptions
-#include "js/RootingAPI.h"                // JS::Rooted
-#include "js/SourceText.h"                // JS::Source{Ownership,Text}
-#include "js/TypeDecls.h"                 // JSFunction, JSObject
-#include "jsapi-tests/tests.h"
-
-BEGIN_TEST(test_cloneScript) {
-  JS::RootedObject A(cx, createGlobal());
-  JS::RootedObject B(cx, createGlobal());
-
-  CHECK(A);
-  CHECK(B);
-
-  static const char source[] =
-      "var i = 0;\n"
-      "var sum = 0;\n"
-      "while (i < 10) {\n"
-      "    sum += i;\n"
-      "    ++i;\n"
-      "}\n"
-      "(sum);\n";
-
-  JS::RootedObject obj(cx);
-
-  // compile for A
-  {
-    JSAutoRealm a(cx, A);
-
-    JS::SourceText<mozilla::Utf8Unit> srcBuf;
-    CHECK(srcBuf.init(cx, source, mozilla::ArrayLength(source) - 1,
-                      JS::SourceOwnership::Borrowed));
-
-    JS::CompileOptions options(cx);
-    options.setFileAndLine(__FILE__, 1);
-
-    JS::RootedFunction fun(cx);
-    JS::RootedObjectVector emptyScopeChain(cx);
-    fun = JS::CompileFunction(cx, emptyScopeChain, options, "f", 0, nullptr,
-                              srcBuf);
-    CHECK(fun);
-    CHECK(obj = JS_GetFunctionObject(fun));
-  }
-
-  // clone into B
-  {
-    JSAutoRealm b(cx, B);
-    CHECK(JS::CloneFunctionObject(cx, obj));
-  }
-
-  return true;
-}
-END_TEST(test_cloneScript)
-
-struct Principals final : public JSPrincipals {
- public:
-  Principals() { refcount = 0; }
-
-  bool write(JSContext* cx, JSStructuredCloneWriter* writer) override {
-    MOZ_ASSERT(false, "not imlemented");
-    return false;
-  }
-
-  bool isSystemOrAddonPrincipal() override { return true; }
-};
-
-static void DestroyPrincipals(JSPrincipals* principals) {
-  auto p = static_cast<Principals*>(principals);
-  delete p;
-}
-
-BEGIN_TEST(test_cloneScriptWithPrincipals) {
-  JS_InitDestroyPrincipalsCallback(cx, DestroyPrincipals);
-
-  JS::AutoHoldPrincipals principalsA(cx, new Principals());
-  JS::AutoHoldPrincipals principalsB(cx, new Principals());
-
-  JS::RootedObject A(cx, createGlobal(principalsA.get()));
-  JS::RootedObject B(cx, createGlobal(principalsB.get()));
-
-  CHECK(A);
-  CHECK(B);
-
-  const char* argnames[] = {"arg"};
-  static const char source[] = "return function() { return arg; }";
-
-  JS::RootedObject obj(cx);
-
-  // Compile in A
-  {
-    JSAutoRealm a(cx, A);
-
-    JS::SourceText<mozilla::Utf8Unit> srcBuf;
-    CHECK(srcBuf.init(cx, source, mozilla::ArrayLength(source) - 1,
-                      JS::SourceOwnership::Borrowed));
-
-    JS::CompileOptions options(cx);
-    options.setFileAndLine(__FILE__, 1);
-
-    JS::RootedFunction fun(cx);
-    JS::RootedObjectVector emptyScopeChain(cx);
-    fun = JS::CompileFunction(cx, emptyScopeChain, options, "f",
-                              mozilla::ArrayLength(argnames), argnames, srcBuf);
-    CHECK(fun);
-
-    JSScript* script;
-    CHECK(script = JS_GetFunctionScript(cx, fun));
-
-    CHECK(JS_GetScriptPrincipals(script) == principalsA.get());
-    CHECK(obj = JS_GetFunctionObject(fun));
-  }
-
-  // Clone into B
-  {
-    JSAutoRealm b(cx, B);
-    JS::RootedObject cloned(cx);
-    CHECK(cloned = JS::CloneFunctionObject(cx, obj));
-
-    JS::RootedFunction fun(cx);
-    JS::RootedValue clonedValue(cx, JS::ObjectValue(*cloned));
-    CHECK(fun = JS_ValueToFunction(cx, clonedValue));
-
-    JSScript* script;
-    CHECK(script = JS_GetFunctionScript(cx, fun));
-
-    CHECK(JS_GetScriptPrincipals(script) == principalsB.get());
-
-    JS::RootedValue v(cx);
-    JS::RootedValue arg(cx, JS::Int32Value(1));
-    CHECK(JS_CallFunctionValue(cx, B, clonedValue, JS::HandleValueArray(arg),
-                               &v));
-    CHECK(v.isObject());
-
-    JSObject* funobj = &v.toObject();
-    CHECK(JS_ObjectIsFunction(funobj));
-    CHECK(fun = JS_ValueToFunction(cx, v));
-    CHECK(script = JS_GetFunctionScript(cx, fun));
-    CHECK(JS_GetScriptPrincipals(script) == principalsB.get());
-  }
-
-  return true;
-}
-END_TEST(test_cloneScriptWithPrincipals)
diff --git a/js/src/jsapi.cpp b/js/src/jsapi.cpp
index f9bc5ee590..c2b27c7e19 100644
--- a/js/src/jsapi.cpp
+++ b/js/src/jsapi.cpp
@@ -3282,105 +3282,6 @@ JS_PUBLIC_API JSFunction* JS::NewFunctionFromSpec(JSContext* cx,
   return NewFunctionFromSpec(cx, fs, id);
 }
 
-static bool IsFunctionCloneable(HandleFunction fun) {
-  // If a function was compiled with non-global syntactic environments on
-  // the environment chain, we could have baked in EnvironmentCoordinates
-  // into the script. We cannot clone it without breaking the compiler's
-  // assumptions.
-  for (ScopeIter si(fun->nonLazyScript()->enclosingScope()); si; si++) {
-    if (si.scope()->is<GlobalScope>()) {
-      return true;
-    }
-    if (si.hasSyntacticEnvironment()) {
-      return false;
-    }
-  }
-
-  return true;
-}
-
-static JSObject* CloneFunctionObject(JSContext* cx, HandleObject funobj,
-                                     HandleObject env, HandleScope scope) {
-  AssertHeapIsIdle();
-  CHECK_THREAD(cx);
-  cx->check(env);
-  MOZ_ASSERT(env);
-  // Note that funobj can be in a different compartment.
-
-  if (!funobj->is<JSFunction>()) {
-    MOZ_RELEASE_ASSERT(!IsCrossCompartmentWrapper(funobj));
-    AutoRealm ar(cx, funobj);
-    RootedValue v(cx, ObjectValue(*funobj));
-    ReportIsNotFunction(cx, v);
-    return nullptr;
-  }
-
-  // Only allow cloning normal, interpreted functions.
-  RootedFunction fun(cx, &funobj->as<JSFunction>());
-  if (fun->isNativeFun() || fun->isBoundFunction() ||
-      fun->kind() != FunctionFlags::NormalFunction || fun->isExtended() ||
-      fun->isSelfHostedBuiltin()) {
-    JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
-                              JSMSG_CANT_CLONE_OBJECT);
-    return nullptr;
-  }
-
-  if (fun->hasSelfHostedLazyScript()) {
-    AutoRealm ar(cx, fun);
-    if (!JSFunction::getOrCreateScript(cx, fun)) {
-      return nullptr;
-    }
-  }
-  RootedScript script(cx, fun->nonLazyScript());
-
-  if (!IsFunctionCloneable(fun)) {
-    JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
-                              JSMSG_BAD_CLONE_FUNOBJ_SCOPE);
-    return nullptr;
-  }
-
-  if (CanReuseScriptForClone(cx->realm(), fun, env)) {
-    return CloneFunctionReuseScript(cx, fun, env, fun->getAllocKind(),
-                                    nullptr);
-  }
-
-  Rooted<ScriptSourceObject*> sourceObject(cx, script->sourceObject());
-  if (cx->compartment() != sourceObject->compartment()) {
-    sourceObject = ScriptSourceObject::clone(cx, sourceObject);
-    if (!sourceObject) {
-      return nullptr;
-    }
-  }
-
-  JSFunction* clone = CloneFunctionAndScript(cx, fun, env, scope, sourceObject,
-                                             fun->getAllocKind());
-
-#ifdef DEBUG
-  // The cloned function should itself be cloneable.
-  RootedFunction cloneRoot(cx, clone);
-  MOZ_ASSERT_IF(cloneRoot, IsFunctionCloneable(cloneRoot));
-#endif
-
-  return clone;
-}
-
-JS_PUBLIC_API JSObject* JS::CloneFunctionObject(JSContext* cx,
-                                                HandleObject funobj) {
-  RootedObject globalLexical(cx, &cx->global()->lexicalEnvironment());
-  RootedScope emptyGlobalScope(cx, &cx->global()->emptyGlobalScope());
-  return CloneFunctionObject(cx, funobj, globalLexical, emptyGlobalScope);
-}
-
-extern JS_PUBLIC_API JSObject* JS::CloneFunctionObject(
-    JSContext* cx, HandleObject funobj, HandleObjectVector envChain) {
-  RootedObject env(cx);
-  RootedScope scope(cx);
-  if (!CreateNonSyntacticEnvironmentChain(cx, envChain, &env)) {
-    return nullptr;
-  }
-  return CloneFunctionObject(cx, funobj, env, scope);
-}
-
 JS_PUBLIC_API JSObject* JS_GetFunctionObject(JSFunction* fun) { return fun; }
 
 JS_PUBLIC_API JSString* JS_GetFunctionId(JSFunction* fun) {
@@ -5700,19 +5601,6 @@ JS_PUBLIC_API JS::TranscodeResult JS::EncodeScript(JSContext* cx,
   return JS::TranscodeResult::Ok;
 }
 
-JS_PUBLIC_API JS::TranscodeResult JS::EncodeInterpretedFunction(
-    JSContext* cx, TranscodeBuffer& buffer, HandleObject funobjArg) {
-  XDREncoder encoder(cx, buffer, buffer.length());
-  RootedFunction funobj(cx, &funobjArg->as<JSFunction>());
-  XDRResult res = encoder.codeFunction(&funobj);
-  if (res.isErr()) {
-    buffer.clearAndFree();
-    return res.unwrapErr();
-  }
-  MOZ_ASSERT(!buffer.empty());
-  return JS::TranscodeResult::Ok;
-}
-
 JS_PUBLIC_API JS::TranscodeResult JS::DecodeScript(
     JSContext* cx, const ReadOnlyCompileOptions& options,
     TranscodeBuffer& buffer, JS::MutableHandleScript scriptp,
@@ -5804,24 +5692,6 @@ JS_PUBLIC_API JS::TranscodeResult JS::DecodeScript(
   return JS::TranscodeResult::Ok;
 }
 
-JS_PUBLIC_API JS::TranscodeResult JS::DecodeInterpretedFunction(
-    JSContext* cx, const ReadOnlyCompileOptions& options,
-    TranscodeBuffer& buffer, JS::MutableHandleFunction funp,
-    size_t cursorIndex) {
-  Rooted<UniquePtr<XDRDecoder>> decoder(
-      cx, js::MakeUnique<XDRDecoder>(cx, &options, buffer, cursorIndex));
-  if (!decoder) {
-    ReportOutOfMemory(cx);
-    return JS::TranscodeResult::Throw;
-  }
-  XDRResult res = decoder->codeFunction(funp);
-  MOZ_ASSERT(bool(funp) == res.isOk());
-  if (res.isErr()) {
-    return res.unwrapErr();
-  }
-  return JS::TranscodeResult::Ok;
-}
-
 JS_PUBLIC_API JS::TranscodeResult JS::DecodeScriptAndStartIncrementalEncoding(
     JSContext* cx, const ReadOnlyCompileOptions& options,
     TranscodeBuffer& buffer, JS::MutableHandleScript scriptp,
diff --git a/js/src/jsapi.h b/js/src/jsapi.h
index c950cbd1e5..10ba58fb2c 100644
--- a/js/src/jsapi.h
+++ b/js/src/jsapi.h
@@ -1676,25 +1676,6 @@ extern JS_PUBLIC_API bool JS_IsFunctionBound(JSFunction* fun);
 
 extern JS_PUBLIC_API JSObject* JS_GetBoundFunctionTarget(JSFunction* fun);
 
-namespace JS {
-
-/**
- * Clone a top-level function into cx's global. This function will dynamically
- * fail if funobj was lexically nested inside some other function.
- */
-extern JS_PUBLIC_API JSObject* CloneFunctionObject(JSContext* cx,
-                                                   HandleObject funobj);
-
-/**
- * As above, but providing an explicit scope chain.  scopeChain must not include
- * the global object on it; that's implicit.  It needs to contain the other
- * objects that should end up on the clone's scope chain.
- */
-extern JS_PUBLIC_API JSObject* CloneFunctionObject(
-    JSContext* cx, HandleObject funobj, HandleObjectVector scopeChain);
-
-}  // namespace JS
-
 extern JS_PUBLIC_API JSObject* JS_GetGlobalFromScript(JSScript* script);
 
 extern JS_PUBLIC_API const char* JS_GetScriptFilename(JSScript* script);
diff --git a/js/src/jsfriendapi.h b/js/src/jsfriendapi.h
index 0035b7d0a7..76ae2ec229 100644
--- a/js/src/jsfriendapi.h
+++ b/js/src/jsfriendapi.h
@@ -190,26 +190,6 @@ extern JS_FRIEND_API bool GetIsSecureContext(JS::Realm* realm);
 extern JS_FRIEND_API bool JS_CopyOwnPropertiesAndPrivateFields(
     JSContext* cx, JS::HandleObject target, JS::HandleObject obj);
 
-/*
- * Single-property version of the above. This function asserts that an |own|
- * property of the given name exists on |obj|.
- *
- * On entry, |cx| must be same-compartment with |obj|. |target| must not be a
- * cross-compartment wrapper because we have to enter its realm.
- *
- * The copyBehavior argument controls what happens with
- * non-configurable properties.
- */
-typedef enum {
-  MakeNonConfigurableIntoConfigurable,
-  CopyNonConfigurableAsIs
-} PropertyCopyBehavior;
-
-extern JS_FRIEND_API bool JS_CopyPropertyFrom(
-    JSContext* cx, JS::HandleId id, JS::HandleObject target,
-    JS::HandleObject obj,
-    PropertyCopyBehavior copyBehavior = CopyNonConfigurableAsIs);
-
 extern JS_FRIEND_API bool JS_WrapPropertyDescriptor(
     JSContext* cx, JS::MutableHandle<JS::PropertyDescriptor> desc);
 
diff --git a/js/src/shell/js.cpp b/js/src/shell/js.cpp
index defa0fe6d9..cace6c54a7 100644
--- a/js/src/shell/js.cpp
+++ b/js/src/shell/js.cpp
@@ -3852,59 +3852,6 @@ static bool Intern(JSContext* cx, unsigned argc, Value* vp) {
   return true;
 }
 
-static bool Clone(JSContext* cx, unsigned argc, Value* vp) {
-  CallArgs args = CallArgsFromVp(argc, vp);
-
-  if (args.length() == 0) {
-    JS_ReportErrorASCII(cx, "Invalid arguments to clone");
-    return false;
-  }
-
-  RootedObject funobj(cx);
-  {
-    Maybe<JSAutoRealm> ar;
-    RootedObject obj(cx, args[0].isPrimitive() ? nullptr : &args[0].toObject());
-
-    if (obj && obj->is<CrossCompartmentWrapperObject>()) {
-      obj = UncheckedUnwrap(obj);
-      ar.emplace(cx, obj);
-      args[0].setObject(*obj);
-    }
-    if (obj && obj->is<JSFunction>()) {
-      funobj = obj;
-    } else {
-      JSFunction* fun = JS_ValueToFunction(cx, args[0]);
-      if (!fun) {
-        return false;
-      }
-      funobj = JS_GetFunctionObject(fun);
-    }
-  }
-
-  RootedObject env(cx);
-  if (args.length() > 1) {
-    if (!JS_ValueToObject(cx, args[1], &env)) {
-      return false;
-    }
-  } else {
-    env = JS::CurrentGlobalOrNull(cx);
-    MOZ_ASSERT(env);
-  }
-
-  // Should it worry us that we might be getting with wrappers
-  // around with wrappers here?
-  JS::RootedObjectVector envChain(cx);
-  if (env && !env->is<GlobalObject>() && !envChain.append(env)) {
-    return false;
-  }
-  JSObject* clone = JS::CloneFunctionObject(cx, funobj, envChain);
-  if (!clone) {
-    return false;
-  }
-  args.rval().setObject(*clone);
-  return true;
-}
-
 static bool Crash(JSContext* cx, unsigned argc, Value* vp) {
   CallArgs args = CallArgsFromVp(argc, vp);
   if (args.length() == 0) {
@@ -8717,10 +8664,6 @@ static bool TransplantableObject(JSContext* cx, unsigned argc, Value* vp) {
 
 // clang-format off
 static const JSFunctionSpecWithHelp shell_functions[] = {
-    JS_FN_HELP("clone", Clone, 1, 0,
-"clone(fun[, scope])",
-"  Clone function object."),
-
     JS_FN_HELP("options", Options, 0, 0,
 "options([option ...])",
 "  Get or toggle JavaScript options."),
diff --git a/js/src/tests/non262/async-functions/clone.js b/js/src/tests/non262/async-functions/clone.js
index 3ca2838223..42d4b883df 100644
--- a/js/src/tests/non262/async-functions/clone.js
+++ b/js/src/tests/non262/async-functions/clone.js
@@ -1,17 +1,4 @@
-// |reftest| skip-if(!xulRuntime.shell) -- needs clone, cloneAndExecuteScript, drainJobQueue
-
-// Async functions can be cloned.
-let f = clone(async function f() {
-  var a = await 1;
-  var b = await 2;
-  var c = await 3;
-  return a + b + c;
-});
-
-var V;
-f().then(v => V = v);
-drainJobQueue();
-assertEq(V, 6);
+// |reftest| skip-if(!xulRuntime.shell) -- needs cloneAndExecuteScript, drainJobQueue
 
 // Async function source code scripts can be cloned.
 let g = newGlobal();
diff --git a/js/src/tests/non262/extensions/regress-300079.js b/js/src/tests/non262/extensions/regress-300079.js
index 2d47faea8f..86457687c9 100644
--- a/js/src/tests/non262/extensions/regress-300079.js
+++ b/js/src/tests/non262/extensions/regress-300079.js
@@ -25,12 +25,10 @@ function test()
   else {
     expect = 'PASSED';
 
-    f = evaluate("(function () { return a * a; })");
-    g = clone(f, {a: 3});
-    f = null;
+    f = evaluate("(function () { return a * a; })", {envChainObject: {a: 3}});
     gc();
     try {
-      a_squared = g(2);
+      a_squared = f(2);
       if (a_squared != 9)
         throw "Unexpected return from g: a_squared == " + a_squared;
       actual = "PASSED";
diff --git a/js/src/tests/non262/regress/regress-127557.js b/js/src/tests/non262/regress/regress-127557.js
deleted file mode 100644
index 573f0ee35a..0000000000
--- a/js/src/tests/non262/regress/regress-127557.js
+++ /dev/null
@@ -1,76 +0,0 @@
-/* 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/. */
-
-/*
- *
- * Date:    06 Mar 2002
- * SUMMARY: Testing cloned function objects
- * See http://bugzilla.mozilla.org/show_bug.cgi?id=127557
- *
- * Before this bug was fixed, this testcase would error when run:
- *
- *             ReferenceError: h_peer is not defined
- *
- * The line |g.prototype = new Object| below is essential: this is
- * what was confusing the engine in its attempt to look up h_peer
- */
-//-----------------------------------------------------------------------------
-var UBound = 0;
-var BUGNUMBER = 127557;
-var summary = 'Testing cloned function objects';
-var cnCOMMA = ',';
-var status = '';
-var statusitems = [];
-var actual = '';
-var actualvalues = [];
-var expect= '';
-var expectedvalues = [];
-
-if (typeof clone == 'function')
-{
-  status = inSection(1);
-  var f = evaluate("(function(x, y) {\n" +
-                   "    function h() { return h_peer(); }\n" +
-                   "    function h_peer() { return (x + cnCOMMA + y); }\n" +
-                   "    return h;\n" +
-                   "})");
-  var g = clone(f);
-  g.prototype = new Object;
-  var h = g(5,6);
-  actual = h();
-  expect = '5,6';
-  addThis();
-}
-else
-{
-  reportCompare('Test not run', 'Test not run', 'shell only test requires clone()');
-}
-
-
-
-//-----------------------------------------------------------------------------
-test();
-//-----------------------------------------------------------------------------
-
-
-
-function addThis()
-{
-  statusitems[UBound] = status;
-  actualvalues[UBound] = actual;
-  expectedvalues[UBound] = expect;
-  UBound++;
-}
-
-
-function test()
-{
-  printBugNumber(BUGNUMBER);
-  printStatus(summary);
-
-  for (var i=0; i<UBound; i++)
-  {
-    reportCompare(expectedvalues[i], actualvalues[i], statusitems[i]);
-  }
-}
diff --git a/js/src/vm/JSObject.cpp b/js/src/vm/JSObject.cpp
index e295b60e0d..512143b543 100644
--- a/js/src/vm/JSObject.cpp
+++ b/js/src/vm/JSObject.cpp
@@ -1012,9 +1012,8 @@ bool JSObject::nonNativeSetElement(JSContext* cx, HandleObject obj,
   return nonNativeSetProperty(cx, obj, id, v, receiver, result);
 }
 
-JS_FRIEND_API bool JS_CopyPropertyFrom(JSContext* cx, HandleId id,
-                                       HandleObject target, HandleObject obj,
-                                       PropertyCopyBehavior copyBehavior) {
+static bool CopyPropertyFrom(JSContext* cx, HandleId id, HandleObject target,
+                             HandleObject obj) {
   // |target| must not be a CCW because we need to enter its realm below and
   // CCWs are not associated with a single realm.
   MOZ_ASSERT(!IsCrossCompartmentWrapper(target));
@@ -1036,11 +1035,6 @@ JS_FRIEND_API bool JS_CopyPropertyFrom(JSContext* cx, HandleId id,
     return true;
   }
 
-  if (copyBehavior == MakeNonConfigurableIntoConfigurable) {
-    // Mask off the JSPROP_PERMANENT bit.
-    desc.attributesRef() &= ~JSPROP_PERMANENT;
-  }
-
   JSAutoRealm ar(cx, target);
   cx->markId(id);
   RootedId wrappedId(cx, id);
@@ -1070,7 +1064,7 @@ JS_FRIEND_API bool JS_CopyOwnPropertiesAndPrivateFields(JSContext* cx,
   }
 
   for (size_t i = 0; i < props.length(); ++i) {
-    if (!JS_CopyPropertyFrom(cx, props[i], target, obj)) {
+    if (!CopyPropertyFrom(cx, props[i], target, obj)) {
       return false;
     }
   }
diff --git a/js/xpconnect/crashtests/471366-1.html b/js/xpconnect/crashtests/471366-1.html
deleted file mode 100644
index b450d5e12a..0000000000
--- a/js/xpconnect/crashtests/471366-1.html
+++ /dev/null
@@ -1,12 +0,0 @@
-<!DOCTYPE html>
-<html>
-<head>
-<script type="text/javascript">
-
-SpecialPowers.wrap(document).getAnonymousNodes({__proto__: XPCNativeWrapper.prototype});
-
-</script>
-</head>
-<body>
-</body>
-</html>
diff --git a/js/xpconnect/crashtests/crashtests.list b/js/xpconnect/crashtests/crashtests.list
index ab9aa23eaf..066fff7fd6 100644
--- a/js/xpconnect/crashtests/crashtests.list
+++ b/js/xpconnect/crashtests/crashtests.list
@@ -15,7 +15,6 @@ load 420513-1.html
 load 453935-1.html
 load 467693-1.html
 load 468552-1.html
-load 471366-1.html
 load 475185-1.html
 load 475291-1.html
 load 503286-1.html
diff --git a/js/xpconnect/idl/nsIXPConnect.idl b/js/xpconnect/idl/nsIXPConnect.idl
index dbfceb549d..bf11085004 100644
--- a/js/xpconnect/idl/nsIXPConnect.idl
+++ b/js/xpconnect/idl/nsIXPConnect.idl
@@ -267,12 +267,5 @@ interface nsIXPConnect : nsISupports
                                       in JSContextPtr aJSContext,
                                       in const_JSReadOnlyCompileOptionsRef aOptions);
 
-    [noscript] void writeFunction(in nsIObjectOutputStream aStream,
-                                  in JSContextPtr aJSContext,
-                                  in JSObjectPtr aJSObject);
-
-    [noscript] JSObjectPtr readFunction(in nsIObjectInputStream aStream,
-                                        in JSContextPtr aJSContext);
-
     [infallible] readonly attribute boolean isShuttingDown;
 };
diff --git a/js/xpconnect/src/Sandbox.cpp b/js/xpconnect/src/Sandbox.cpp
index 85dfc67a1f..842789eded 100644
--- a/js/xpconnect/src/Sandbox.cpp
+++ b/js/xpconnect/src/Sandbox.cpp
@@ -66,9 +66,13 @@
 #include "mozilla/dom/XMLHttpRequest.h"
 #include "mozilla/dom/XMLSerializerBinding.h"
 #include "mozilla/dom/FormDataBinding.h"
+#include "mozilla/dom/nsCSPContext.h"
 #include "mozilla/BasePrincipal.h"
 #include "mozilla/DeferredFinalize.h"
+#include "mozilla/ExtensionPolicyService.h"
 #include "mozilla/NullPrincipal.h"
+#include "mozilla/ResultExtensions.h"
+#include "mozilla/StaticPrefs_extensions.h"
 
 using namespace mozilla;
 using namespace JS;
@@ -336,6 +340,46 @@ static bool SandboxCreateFetch(JSContext* cx, HandleObject obj) {
          dom::Headers_Binding::GetConstructorObject(cx);
 }
 
+static bool SandboxStructuredClone(JSContext* cx, unsigned argc, Value* vp) {
+  CallArgs args = CallArgsFromVp(argc, vp);
+
+  if (!args.requireAtLeast(cx, "structuredClone", 1)) {
+    return false;
+  }
+
+  RootedDictionary<dom::StructuredSerializeOptions> options(cx);
+  BindingCallContext callCx(cx, "structuredClone");
+  if (!options.Init(cx, args.hasDefined(1) ? args[1] : JS::NullHandleValue,
+                    "Argument 2", false)) {
+    return false;
+  }
+
+  nsIGlobalObject* global = CurrentNativeGlobal(cx);
+  if (!global) {
+    JS_ReportErrorASCII(cx, "structuredClone: Missing global");
+    return false;
+  }
+
+  JS::Rooted<JS::Value> result(cx);
+  ErrorResult rv;
+  nsContentUtils::StructuredClone(cx, global, args[0], options, &result, rv);
+  if (rv.MaybeSetPendingException(cx)) {
+    return false;
+  }
+
+  MOZ_ASSERT_IF(result.isGCThing(),
+                !JS::GCThingIsMarkedGray(result.toGCCellPtr()));
+  args.rval().set(result);
+  return true;
+}
+
+static bool SandboxCreateStructuredClone(JSContext* cx, HandleObject obj) {
+  MOZ_ASSERT(JS_IsGlobalObject(obj));
+
+  return JS_DefineFunction(cx, obj, "structuredClone", SandboxStructuredClone,
+                           1, 0);
+}
+
 static bool SandboxIsProxy(JSContext* cx, unsigned argc, Value* vp) {
   CallArgs args = CallArgsFromVp(argc, vp);
   if (args.length() < 1) {
@@ -880,6 +924,8 @@ bool xpc::GlobalProperties::Parse(JSContext* cx, JS::HandleObject obj) {
       crypto = true;
     } else if (JS_LinearStringEqualsLiteral(nameStr, "fetch")) {
       fetch = true;
+    } else if (JS_LinearStringEqualsLiteral(nameStr, "structuredClone")) {
+      structuredClone = true;
     } else if (JS_LinearStringEqualsLiteral(nameStr, "indexedDB")) {
       indexedDB = true;
 #ifdef MOZ_WEBRTC
@@ -1000,6 +1046,10 @@ bool xpc::GlobalProperties::Define(JSContext* cx, JS::HandleObject obj) {
     return false;
   }
 
+  if (structuredClone && !SandboxCreateStructuredClone(cx, obj)) {
+    return false;
+  }
+
 #ifdef MOZ_WEBRTC
   if (rtcIdentityProvider && !SandboxCreateRTCIdentityProvider(cx, obj)) {
     return false;
@@ -1029,6 +1079,75 @@ bool xpc::GlobalProperties::DefineInSandbox(JSContext* cx,
   return Define(cx, obj);
 }
 
+/**
+ * If enabled, apply the extension base CSP, then apply the
+ * content script CSP which will either be a default or one
+ * provided by the extension in its manifest.
+ */
+nsresult ApplyAddonContentScriptCSP(nsISupports* prinOrSop) {
+  if (!StaticPrefs::extensions_content_script_csp_enabled()) {
+    return NS_OK;
+  }
+  nsCOMPtr<nsIPrincipal> principal = do_QueryInterface(prinOrSop);
+  if (!principal) {
+    return NS_OK;
+  }
+
+  auto* basePrin = BasePrincipal::Cast(principal);
+  // We only get an addonPolicy if the principal is an
+  // expanded principal with an extension principal in it.
+  auto* addonPolicy = basePrin->ContentScriptAddonPolicy();
+  if (!addonPolicy) {
+    return NS_OK;
+  }
+
+  nsString url;
+  MOZ_TRY_VAR(url, addonPolicy->GetURL(NS_LITERAL_STRING("")));
+
+  nsCOMPtr<nsIURI> selfURI;
+  MOZ_TRY(NS_NewURI(getter_AddRefs(selfURI), url));
+
+  nsAutoString baseCSP;
+  MOZ_ALWAYS_SUCCEEDS(
+      ExtensionPolicyService::GetSingleton().GetBaseCSP(baseCSP));
+
+  // If we got here, we're definitly an expanded principal.
+  auto expanded = basePrin->As<ExpandedPrincipal>();
+  nsCOMPtr<nsIContentSecurityPolicy> csp;
+
+#ifdef MOZ_DEBUG
+  // Bug 1548468: Move CSP off ExpandedPrincipal
+  expanded->GetCsp(getter_AddRefs(csp));
+  if (csp) {
+    uint32_t count = 0;
+    csp->GetPolicyCount(&count);
+    if (count > 0) {
+      // Ensure that the policy was not already added.
+      nsAutoString parsedPolicyStr;
+      for (uint32_t i = 0; i < count; i++) {
+        csp->GetPolicyString(i, parsedPolicyStr);
+        MOZ_ASSERT(!parsedPolicyStr.Equals(baseCSP));
+      }
+    }
+  }
+#endif
+
+  csp = new nsCSPContext();
+  MOZ_TRY(
+      csp->SetRequestContextWithPrincipal(expanded, selfURI, EmptyString(), 0));
+
+  bool reportOnly = StaticPrefs::extensions_content_script_csp_report_only();
+
+  MOZ_TRY(csp->AppendPolicy(baseCSP, reportOnly, false));
+
+  // Set default or extension provided csp.
+  const nsAString& contentScriptCSP = addonPolicy->ContentScriptCSP();
+  MOZ_TRY(csp->AppendPolicy(contentScriptCSP, reportOnly, false));
+
+  expanded->SetCsp(csp);
+  return NS_OK;
+}
+
 nsresult xpc::CreateSandboxObject(JSContext* cx, MutableHandleValue vp,
                                   nsISupports* prinOrSop,
                                   SandboxOptions& options) {
@@ -1111,8 +1230,6 @@ nsresult xpc::CreateSandboxObject(JSContext* cx, MutableHandleValue vp,
     MOZ_RELEASE_ASSERT(priv->allowWaivers == options.allowWaivers);
     MOZ_RELEASE_ASSERT(priv->isWebExtensionContentScript ==
                        options.isWebExtensionContentScript);
-    MOZ_RELEASE_ASSERT(priv->isContentXBLCompartment ==
-                       options.isContentXBLScope);
     MOZ_RELEASE_ASSERT(priv->isUAWidgetCompartment == options.isUAWidgetScope);
     MOZ_RELEASE_ASSERT(priv->hasExclusiveExpandos == hasExclusiveExpandos);
     MOZ_RELEASE_ASSERT(priv->wantXrays == wantXrays);
@@ -1120,7 +1237,6 @@ nsresult xpc::CreateSandboxObject(JSContext* cx, MutableHandleValue vp,
     CompartmentPrivate* priv = CompartmentPrivate::Get(sandbox);
     priv->allowWaivers = options.allowWaivers;
     priv->isWebExtensionContentScript = options.isWebExtensionContentScript;
-    priv->isContentXBLCompartment = options.isContentXBLScope;
     priv->isUAWidgetCompartment = options.isUAWidgetScope;
     priv->hasExclusiveExpandos = hasExclusiveExpandos;
     priv->wantXrays = wantXrays;
@@ -1779,6 +1895,8 @@ nsresult nsXPCComponents_utils_Sandbox::CallOrConstruct(
       } else {
         ok = GetExpandedPrincipal(cx, obj, options, getter_AddRefs(expanded));
         prinOrSop = expanded;
+        // If this is an addon content script we need to apply the csp.
+        MOZ_TRY(ApplyAddonContentScriptCSP(prinOrSop));
       }
     } else {
       ok = GetPrincipalOrSOP(cx, obj, getter_AddRefs(prinOrSop));
diff --git a/js/xpconnect/src/XPCJSRuntime.cpp b/js/xpconnect/src/XPCJSRuntime.cpp
index 3798e3165e..3fe3942970 100644
--- a/js/xpconnect/src/XPCJSRuntime.cpp
+++ b/js/xpconnect/src/XPCJSRuntime.cpp
@@ -200,7 +200,6 @@ CompartmentPrivate::CompartmentPrivate(
       wantXrays(false),
       allowWaivers(true),
       isWebExtensionContentScript(false),
-      isContentXBLCompartment(false),
       isUAWidgetCompartment(false),
       hasExclusiveExpandos(false),
       wasShutdown(false),
@@ -497,20 +496,6 @@ Scriptability& Scriptability::Get(JSObject* aScope) {
   return RealmPrivate::Get(aScope)->scriptability;
 }
 
-bool IsContentXBLCompartment(JS::Compartment* compartment) {
-  // We always eagerly create compartment privates for content XBL compartments.
-  CompartmentPrivate* priv = CompartmentPrivate::Get(compartment);
-  return priv && priv->isContentXBLCompartment;
-}
-
-bool IsContentXBLScope(JS::Realm* realm) {
-  return IsContentXBLCompartment(JS::GetCompartmentForRealm(realm));
-}
-
-bool IsInContentXBLScope(JSObject* obj) {
-  return IsContentXBLCompartment(JS::GetCompartment(obj));
-}
-
 bool IsUAWidgetCompartment(JS::Compartment* compartment) {
   // We always eagerly create compartment privates for UA Widget compartments.
   CompartmentPrivate* priv = CompartmentPrivate::Get(compartment);
@@ -2075,11 +2060,7 @@ class OrphanReporter : public JS::ObjectPrivateVisitor {
 
   virtual size_t sizeOfIncludingThis(nsISupports* aSupports) override {
     nsCOMPtr<nsINode> node = do_QueryInterface(aSupports);
-    // https://bugzilla.mozilla.org/show_bug.cgi?id=773533#c11 explains that we
-    // have to skip XBL elements because they violate certain assumptions.  Yuk.
-    if (!node || node->IsInComposedDoc() ||
-        (node->IsElement() &&
-         node->AsElement()->IsInNamespace(kNameSpaceID_XBL))) {
+    if (!node || node->IsInComposedDoc()) {
       return 0;
     }
 
diff --git a/js/xpconnect/src/XPCShellImpl.cpp b/js/xpconnect/src/XPCShellImpl.cpp
index 13d231762d..4223358e11 100644
--- a/js/xpconnect/src/XPCShellImpl.cpp
+++ b/js/xpconnect/src/XPCShellImpl.cpp
@@ -1014,7 +1014,7 @@ static bool GetCurrentWorkingDirectory(nsAString& workingDirectory) {
   // size back down to the actual string length
   cwd.SetLength(strlen(result) + 1);
   cwd.Replace(cwd.Length() - 1, 1, '/');
-  workingDirectory = NS_ConvertUTF8toUTF16(cwd);
+  CopyUTF8toUTF16(cwd, workingDirectory);
 #endif
   return true;
 }
diff --git a/js/xpconnect/src/XPCWrappedNativeScope.cpp b/js/xpconnect/src/XPCWrappedNativeScope.cpp
index 877fc4e66c..c0f08eb5ba 100644
--- a/js/xpconnect/src/XPCWrappedNativeScope.cpp
+++ b/js/xpconnect/src/XPCWrappedNativeScope.cpp
@@ -173,19 +173,6 @@ bool XPCWrappedNativeScope::AttachComponentsObject(JSContext* aCx) {
   return true;
 }
 
-JSObject* XPCWrappedNativeScope::EnsureContentXBLScope(JSContext* cx) {
-  JS::RootedObject global(cx, CurrentGlobalOrNull(cx));
-  MOZ_ASSERT(js::IsObjectInContextCompartment(global, cx));
-  MOZ_ASSERT(!IsContentXBLScope());
-  MOZ_ASSERT(strcmp(js::GetObjectClass(global)->name,
-                    "nsXBLPrototypeScript compilation scope"));
-
-  // We can probably remove EnsureContentXBLScope and clean up all its callers,
-  // but a bunch (all?) of those callers will just go away when we remove XBL
-  // support, so it's simpler to just leave it here as a no-op.
-  return global;
-}
-
 bool XPCWrappedNativeScope::XBLScopeStateMatches(nsIPrincipal* aPrincipal) {
   return mAllowContentXBLScope ==
          !RemoteXULForbidsXBLScopeForPrincipal(aPrincipal);
@@ -199,19 +186,6 @@ bool XPCWrappedNativeScope::AllowContentXBLScope(Realm* aRealm) {
 }
 
 namespace xpc {
-JSObject* GetXBLScope(JSContext* cx, JSObject* contentScopeArg) {
-  JS::RootedObject contentScope(cx, contentScopeArg);
-  JSAutoRealm ar(cx, contentScope);
-  XPCWrappedNativeScope* nativeScope = ObjectScope(contentScope);
-
-  RootedObject scope(cx, nativeScope->EnsureContentXBLScope(cx));
-  NS_ENSURE_TRUE(scope, nullptr);  // See bug 858642.
-
-  scope = js::UncheckedUnwrap(scope);
-  JS::ExposeObjectToActiveJS(scope);
-  return scope;
-}
-
 JSObject* GetUAWidgetScope(JSContext* cx, JSObject* contentScopeArg) {
   JS::RootedObject contentScope(cx, contentScopeArg);
   JSAutoRealm ar(cx, contentScope);
diff --git a/js/xpconnect/src/nsXPConnect.cpp b/js/xpconnect/src/nsXPConnect.cpp
index 2bce0fd6af..912401a208 100644
--- a/js/xpconnect/src/nsXPConnect.cpp
+++ b/js/xpconnect/src/nsXPConnect.cpp
@@ -909,17 +909,10 @@ void SetLocationForGlobal(JSObject* global, nsIURI* locationURI) {
 
 }  // namespace xpc
 
-static nsresult WriteScriptOrFunction(nsIObjectOutputStream* stream,
-                                      JSContext* cx, JSScript* scriptArg,
-                                      HandleObject functionObj) {
-  // Exactly one of script or functionObj must be given
-  MOZ_ASSERT(!scriptArg != !functionObj);
-
+NS_IMETHODIMP
+nsXPConnect::WriteScript(nsIObjectOutputStream* stream, JSContext* cx,
+                         JSScript* scriptArg) {
   RootedScript script(cx, scriptArg);
-  if (!script) {
-    RootedFunction fun(cx, JS_GetObjectFunction(functionObj));
-    script.set(JS_GetFunctionScript(cx, fun));
-  }
 
   uint8_t flags = 0;  // We don't have flags anymore.
   nsresult rv = stream->Write8(flags);
@@ -929,13 +922,7 @@ static nsresult WriteScriptOrFunction(nsIObjectOutputStream* stream,
 
   TranscodeBuffer buffer;
   TranscodeResult code;
-  {
-    if (functionObj) {
-      code = EncodeInterpretedFunction(cx, buffer, functionObj);
-    } else {
-      code = EncodeScript(cx, buffer, script);
-    }
-  }
+  code = EncodeScript(cx, buffer, script);
 
   if (code != TranscodeResult::Ok) {
     if (code == TranscodeResult::Throw) {
@@ -960,14 +947,10 @@ static nsresult WriteScriptOrFunction(nsIObjectOutputStream* stream,
   return rv;
 }
 
-static nsresult ReadScriptOrFunction(nsIObjectInputStream* stream,
-                                     JSContext* cx,
-                                     const JS::ReadOnlyCompileOptions& options,
-                                     JSScript** scriptp,
-                                     JSObject** functionObjp) {
-  // Exactly one of script or functionObj must be given
-  MOZ_ASSERT(!scriptp != !functionObjp);
-
+NS_IMETHODIMP
+nsXPConnect::ReadScript(nsIObjectInputStream* stream, JSContext* cx,
+                        const JS::ReadOnlyCompileOptions& options,
+                        JSScript** scriptp) {
   uint8_t flags;
   nsresult rv = stream->Read8(&flags);
   if (NS_FAILED(rv)) {
@@ -1001,27 +984,14 @@ static nsresult ReadScriptOrFunction(nsIObjectInputStream* stream,
 
   {
     TranscodeResult code;
-    if (scriptp) {
-      Rooted<JSScript*> script(cx);
-      code = DecodeScript(cx, options, buffer, &script);
-      if (code == TranscodeResult::Ok) {
-        *scriptp = script.get();
-      } else {
-        if (code == TranscodeResult::Throw) {
-          JS_ClearPendingException(cx);
-          return NS_ERROR_OUT_OF_MEMORY;
-        }
-      }
+    Rooted<JSScript*> script(cx);
+    code = DecodeScript(cx, options, buffer, &script);
+    if (code == TranscodeResult::Ok) {
+      *scriptp = script.get();
     } else {
-      Rooted<JSFunction*> funobj(cx);
-      code = DecodeInterpretedFunction(cx, options, buffer, &funobj);
-      if (code == TranscodeResult::Ok) {
-        *functionObjp = JS_GetFunctionObject(funobj.get());
-      } else {
-        if (code == TranscodeResult::Throw) {
-          JS_ClearPendingException(cx);
-          return NS_ERROR_OUT_OF_MEMORY;
-        }
+      if (code == TranscodeResult::Throw) {
+        JS_ClearPendingException(cx);
+        return NS_ERROR_OUT_OF_MEMORY;
       }
     }
 
@@ -1032,34 +1002,6 @@ static nsresult ReadScriptOrFunction(nsIObjectInputStream* stream,
   return rv;
 }
 
-NS_IMETHODIMP
-nsXPConnect::WriteScript(nsIObjectOutputStream* stream, JSContext* cx,
-                         JSScript* script) {
-  return WriteScriptOrFunction(stream, cx, script, nullptr);
-}
-
-NS_IMETHODIMP
-nsXPConnect::ReadScript(nsIObjectInputStream* stream, JSContext* cx,
-                        const JS::ReadOnlyCompileOptions& options,
-                        JSScript** scriptp) {
-  return ReadScriptOrFunction(stream, cx, options, scriptp, nullptr);
-}
-
-NS_IMETHODIMP
-nsXPConnect::WriteFunction(nsIObjectOutputStream* stream, JSContext* cx,
-                           JSObject* functionObjArg) {
-  RootedObject functionObj(cx, functionObjArg);
-  return WriteScriptOrFunction(stream, cx, nullptr, functionObj);
-}
-
-NS_IMETHODIMP
-nsXPConnect::ReadFunction(nsIObjectInputStream* stream, JSContext* cx,
-                          JSObject** functionObjp) {
-  JS::CompileOptions compileOptions(cx);
-  return ReadScriptOrFunction(stream, cx, compileOptions, nullptr,
-                              functionObjp);
-}
-
 NS_IMETHODIMP
 nsXPConnect::GetIsShuttingDown(bool* aIsShuttingDown) {
   if (!aIsShuttingDown) {
@@ -1144,8 +1086,7 @@ bool IsChromeOrXBL(JSContext* cx, JSObject* /* unused */) {
   // Note that, for performance, we don't check AllowXULXBLForPrincipal here,
   // and instead rely on the fact that AllowContentXBLScope() only returns false
   // in remote XUL situations.
-  return AccessCheck::isChrome(c) || IsContentXBLCompartment(c) ||
-         !AllowContentXBLScope(realm);
+  return AccessCheck::isChrome(c) || !AllowContentXBLScope(realm);
 }
 
 bool IsNotUAWidget(JSContext* cx, JSObject* /* unused */) {
diff --git a/js/xpconnect/src/xpc.msg b/js/xpconnect/src/xpc.msg
index 37b5b36fa0..475f6b0c37 100644
--- a/js/xpconnect/src/xpc.msg
+++ b/js/xpconnect/src/xpc.msg
@@ -60,7 +60,6 @@ XPC_MSG_DEF(NS_ERROR_XPC_BAD_INITIALIZER_NAME           , "Bad initializer name
 XPC_MSG_DEF(NS_ERROR_XPC_HAS_BEEN_SHUTDOWN              , "Operation failed because the XPConnect subsystem has been shutdown")
 XPC_MSG_DEF(NS_ERROR_XPC_CANT_MODIFY_PROP_ON_WN         , "Cannot modify properties of a WrappedNative")
 XPC_MSG_DEF(NS_ERROR_XPC_BAD_CONVERT_JS_ZERO_ISNOT_NULL , "Could not convert JavaScript argument - 0 was passed, expected object. Did you mean null?")
-XPC_MSG_DEF(NS_ERROR_XPC_CANT_PASS_CPOW_TO_NATIVE       , "It's illegal to pass a CPOW to native code")
 
 
 /* common global codes (from nsError.h) */
diff --git a/js/xpconnect/src/xpcprivate.h b/js/xpconnect/src/xpcprivate.h
index 45f8c0d268..365d303c0b 100644
--- a/js/xpconnect/src/xpcprivate.h
+++ b/js/xpconnect/src/xpcprivate.h
@@ -880,12 +880,6 @@ class XPCWrappedNativeScope final
 
   void AddSizeOfIncludingThis(JSContext* cx, ScopeSizeInfo* scopeSizeInfo);
 
-  // Gets the appropriate scope object for XBL in this compartment. This method
-  // relies on compartment-per-global still (and release-asserts this). The
-  // context must be same-realm with this compartment's single global upon
-  // entering, and the scope object is wrapped into this compartment.
-  JSObject* EnsureContentXBLScope(JSContext* cx);
-
   // Check whether our mAllowContentXBLScope state matches the given
   // principal.  This is used to avoid sharing compartments on
   // mismatch.
@@ -906,9 +900,6 @@ class XPCWrappedNativeScope final
     return js::GetFirstGlobalInCompartment(Compartment());
   }
 
-  bool IsContentXBLScope() {
-    return xpc::IsContentXBLCompartment(Compartment());
-  }
   bool AllowContentXBLScope(JS::Realm* aRealm);
 
   // ID Object prototype caches.
@@ -2296,6 +2287,7 @@ struct GlobalProperties {
   bool caches : 1;
   bool crypto : 1;
   bool fetch : 1;
+  bool structuredClone : 1;
   bool indexedDB : 1;
   bool rtcIdentityProvider : 1;
 
@@ -2346,7 +2338,6 @@ class MOZ_STACK_CLASS SandboxOptions : public OptionsBase {
         sameZoneAs(cx),
         freshCompartment(false),
         freshZone(false),
-        isContentXBLScope(false),
         isUAWidgetScope(false),
         invisibleToDebugger(false),
         discardSource(false),
@@ -2366,7 +2357,6 @@ class MOZ_STACK_CLASS SandboxOptions : public OptionsBase {
   JS::RootedObject sameZoneAs;
   bool freshCompartment;
   bool freshZone;
-  bool isContentXBLScope;
   bool isUAWidgetScope;
   bool invisibleToDebugger;
   bool discardSource;
@@ -2644,8 +2634,7 @@ class CompartmentPrivate {
 
     // Don't share if we have any weird state set.
     return !wantXrays && !isWebExtensionContentScript &&
-           !isContentXBLCompartment && !isUAWidgetCompartment &&
-           mScope->XBLScopeStateMatches(principal);
+           !isUAWidgetCompartment && mScope->XBLScopeStateMatches(principal);
   }
 
   CompartmentOriginInfo originInfo;
@@ -2665,10 +2654,6 @@ class CompartmentPrivate {
   // receives various bits of special compatibility behavior.
   bool isWebExtensionContentScript;
 
-  // True if this compartment is a content XBL compartment. Every global in
-  // such a compartment is a content XBL scope.
-  bool isContentXBLCompartment;
-
   // True if this compartment is a UA widget compartment.
   bool isUAWidgetCompartment;
 
diff --git a/js/xpconnect/src/xpcpublic.h b/js/xpconnect/src/xpcpublic.h
index 52cb6f0d78..7c91e0434f 100644
--- a/js/xpconnect/src/xpcpublic.h
+++ b/js/xpconnect/src/xpcpublic.h
@@ -110,10 +110,6 @@ JSObject* TransplantObjectRetainingXrayExpandos(JSContext* cx,
                                                 JS::HandleObject origobj,
                                                 JS::HandleObject target);
 
-bool IsContentXBLCompartment(JS::Compartment* compartment);
-bool IsContentXBLScope(JS::Realm* realm);
-bool IsInContentXBLScope(JSObject* obj);
-
 bool IsUAWidgetCompartment(JS::Compartment* compartment);
 bool IsUAWidgetScope(JS::Realm* realm);
 bool IsInUAWidgetScope(JSObject* obj);
@@ -122,33 +118,10 @@ bool MightBeWebContentCompartment(JS::Compartment* compartment);
 
 void SetCompartmentChangedDocumentDomain(JS::Compartment* compartment);
 
-// Return a raw XBL scope object corresponding to contentScope, which must
-// be an object whose global is a DOM window.
-//
-// The return value is not wrapped into cx->compartment, so be sure to enter
-// its compartment before doing anything meaningful.
-//
-// Also note that XBL scopes are lazily created, so the return-value should be
-// null-checked unless the caller can ensure that the scope must already
-// exist.
-//
-// This function asserts if |contentScope| is itself in an XBL scope to catch
-// sloppy consumers. Conversely, GetXBLScopeOrGlobal will handle objects that
-// are in XBL scope (by just returning the global).
-JSObject* GetXBLScope(JSContext* cx, JSObject* contentScope);
-
 JSObject* GetUAWidgetScope(JSContext* cx, nsIPrincipal* principal);
 
 JSObject* GetUAWidgetScope(JSContext* cx, JSObject* contentScope);
 
-inline JSObject* GetXBLScopeOrGlobal(JSContext* cx, JSObject* obj) {
-  MOZ_ASSERT(!js::IsCrossCompartmentWrapper(obj));
-  if (IsInContentXBLScope(obj)) {
-    return JS::GetNonCCWObjectGlobal(obj);
-  }
-  return GetXBLScope(cx, obj);
-}
-
 // Returns whether XBL scopes have been explicitly disabled for code running
 // in this compartment. See the comment around mAllowContentXBLScope.
 bool AllowContentXBLScope(JS::Realm* realm);
diff --git a/js/xpconnect/tests/chrome/bug503926.xul b/js/xpconnect/tests/chrome/bug503926.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/bug503926.xul
rename to js/xpconnect/tests/chrome/bug503926.xhtml
diff --git a/js/xpconnect/tests/chrome/chrome.ini b/js/xpconnect/tests/chrome/chrome.ini
index 9985686aa8..fdce22f39c 100644
--- a/js/xpconnect/tests/chrome/chrome.ini
+++ b/js/xpconnect/tests/chrome/chrome.ini
@@ -1,11 +1,10 @@
 [DEFAULT]
 skip-if = os == 'android'
 support-files =
-  bug503926.xul
+  bug503926.xhtml
   file_bug484459.html
-  file_bug618176.xul
+  file_bug618176.xhtml
   file_bug996069.html
-  file_bug1050049.xml
   file_bug1281071.html
   file_discardSystemSource.html
   file_empty.html
@@ -22,7 +21,6 @@ support-files =
   !/js/xpconnect/tests/mochitest/file_bug738244.html
   !/js/xpconnect/tests/mochitest/file_bug760131.html
   !/js/xpconnect/tests/mochitest/file_bug795275.html
-  !/js/xpconnect/tests/mochitest/file_bug795275.xml
   !/js/xpconnect/tests/mochitest/file_bug799348.html
   !/js/xpconnect/tests/mochitest/file_bug860494.html
   !/js/xpconnect/tests/mochitest/file_documentdomain.html
@@ -37,92 +35,91 @@ prefs =
   javascript.options.experimental.private_fields=true
   javascript.options.large_arraybuffers=true
 
-[test_APIExposer.xul]
-[test_bug361111.xul]
-[test_bug448587.xul]
-[test_bug484459.xul]
+[test_APIExposer.xhtml]
+[test_bug361111.xhtml]
+[test_bug448587.xhtml]
+[test_bug484459.xhtml]
 skip-if = os == 'win' || os == 'mac' || (os == 'linux' && !debug) # bug 1131110, 1255284
-[test_bug500931.xul]
-[test_bug503926.xul]
-[test_bug533596.xul]
-[test_bug571849.xul]
-[test_bug596580.xul]
-[test_bug610390.xul]
-[test_bug614757.xul]
-[test_bug616992.xul]
-[test_bug618176.xul]
-[test_bug654370.xul]
-[test_bug658560.xul]
-[test_bug658909.xul]
-[test_bug664689.xul]
-[test_bug679861.xul]
-[test_bug706301.xul]
-[test_bug726949.xul]
-[test_bug732665.xul]
-[test_bug738244.xul]
-[test_bug743843.xul]
-[test_bug760076.xul]
+[test_bug500931.xhtml]
+[test_bug503926.xhtml]
+[test_bug533596.xhtml]
+[test_bug571849.xhtml]
+[test_bug596580.xhtml]
+[test_bug610390.xhtml]
+[test_bug614757.xhtml]
+[test_bug616992.xhtml]
+[test_bug618176.xhtml]
+[test_bug654370.xhtml]
+[test_bug658560.xhtml]
+[test_bug658909.xhtml]
+[test_bug664689.xhtml]
+[test_bug679861.xhtml]
+[test_bug706301.xhtml]
+[test_bug726949.xhtml]
+[test_bug732665.xhtml]
+[test_bug738244.xhtml]
+[test_bug743843.xhtml]
+[test_bug760076.xhtml]
 [test_bug760131.html]
-[test_bug763343.xul]
-[test_bug771429.xul]
-[test_bug773962.xul]
-[test_bug792280.xul]
-[test_bug793433.xul]
-[test_bug795275.xul]
-[test_bug799348.xul]
-[test_bug801241.xul]
-[test_bug812415.xul]
-[test_bug853283.xul]
-[test_bug853571.xul]
-[test_bug858101.xul]
-[test_bug860494.xul]
-[test_bug865948.xul]
-[test_bug866823.xul]
-[test_bug895340.xul]
-[test_bug932906.xul]
-[test_bug996069.xul]
-[test_bug1041626.xul]
-[test_bug1042436.xul]
-[test_bug1050049.html]
+[test_bug763343.xhtml]
+[test_bug771429.xhtml]
+[test_bug773962.xhtml]
+[test_bug792280.xhtml]
+[test_bug793433.xhtml]
+[test_bug795275.xhtml]
+[test_bug799348.xhtml]
+[test_bug801241.xhtml]
+[test_bug812415.xhtml]
+[test_bug853283.xhtml]
+[test_bug853571.xhtml]
+[test_bug858101.xhtml]
+[test_bug860494.xhtml]
+[test_bug865948.xhtml]
+[test_bug866823.xhtml]
+[test_bug895340.xhtml]
+[test_bug932906.xhtml]
+[test_bug996069.xhtml]
+[test_bug1041626.xhtml]
+[test_bug1042436.xhtml]
 [test_bug1065185.html]
 [test_bug1074863.html]
-[test_bug1092477.xul]
+[test_bug1092477.xhtml]
 [test_bug1124898.html]
 [test_bug1126911.html]
-[test_bug1281071.xul]
-[test_bug1390159.xul]
+[test_bug1281071.xhtml]
+[test_bug1390159.xhtml]
 [test_bug1430164.html]
 [test_bug1516237.html]
-[test_chrometoSource.xul]
-[test_cloneInto.xul]
-[test_cows.xul]
+[test_chrometoSource.xhtml]
+[test_cloneInto.xhtml]
+[test_cows.xhtml]
 [test_private_field_cows.xhtml]
-[test_discardSystemSource.xul]
-[test_documentdomain.xul]
-[test_doublewrappedcompartments.xul]
-[test_evalInSandbox.xul]
-[test_evalInWindow.xul]
-[test_exnstack.xul]
-[test_expandosharing.xul]
-[test_exposeInDerived.xul]
-[test_localstorage_with_nsEp.xul]
-[test_matches.xul]
-[test_nodelists.xul]
+[test_discardSystemSource.xhtml]
+[test_documentdomain.xhtml]
+[test_doublewrappedcompartments.xhtml]
+[test_evalInSandbox.xhtml]
+[test_evalInWindow.xhtml]
+[test_exnstack.xhtml]
+[test_expandosharing.xhtml]
+[test_exposeInDerived.xhtml]
+[test_localstorage_with_nsEp.xhtml]
+[test_matches.xhtml]
+[test_nodelists.xhtml]
 [test_nsScriptErrorWithStack.html]
 [test_onGarbageCollection.html]
-[test_precisegc.xul]
-[test_sandboxImport.xul]
-[test_scriptSettings.xul]
+[test_precisegc.xhtml]
+[test_sandboxImport.xhtml]
+[test_scriptSettings.xhtml]
 [test_scripterror.html]
 [test_sharedChromeCompartment.html]
-[test_weakmap_keys_preserved.xul]
-[test_weakmap_keys_preserved2.xul]
-[test_weakref.xul]
+[test_weakmap_keys_preserved.xhtml]
+[test_weakmap_keys_preserved2.xhtml]
+[test_weakref.xhtml]
 [test_windowProxyDeadWrapper.html]
-[test_wrappers.xul]
-[test_xrayic.xul]
+[test_wrappers.xhtml]
+[test_xrayic.xhtml]
 [test_xrayLargeTypedArray.html]
 skip-if = bits == 32 # Large ArrayBuffers not supported on 32-bit.
-[test_xrayToJS.xul]
+[test_xrayToJS.xhtml]
 [test_bug1530146.html]
 support-files = file_bug1530146.html file_bug1530146_inner.html
diff --git a/js/xpconnect/tests/chrome/file_bug1050049.xml b/js/xpconnect/tests/chrome/file_bug1050049.xml
deleted file mode 100644
index cc8653ea63..0000000000
--- a/js/xpconnect/tests/chrome/file_bug1050049.xml
+++ /dev/null
@@ -1,10 +0,0 @@
-<?xml version="1.0"?>
-<bindings id="testBindings" xmlns="http://www.mozilla.org/xbl"
-          xmlns:html="http://www.w3.org/1999/xhtml">
-  <binding id="regularChromeBinding">
-    <content><html:p>Anonymous Paragraph</html:p></content>
-  </binding>
-  <binding id="whitelistedChromeBinding" bindToUntrustedContent="true">
-    <content><html:p>Anonymous Paragraph</html:p></content>
-  </binding>
-</bindings>
diff --git a/js/xpconnect/tests/chrome/file_bug618176.xul b/js/xpconnect/tests/chrome/file_bug618176.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/file_bug618176.xul
rename to js/xpconnect/tests/chrome/file_bug618176.xhtml
diff --git a/js/xpconnect/tests/chrome/test_APIExposer.xul b/js/xpconnect/tests/chrome/test_APIExposer.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_APIExposer.xul
rename to js/xpconnect/tests/chrome/test_APIExposer.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug1041626.xul b/js/xpconnect/tests/chrome/test_bug1041626.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug1041626.xul
rename to js/xpconnect/tests/chrome/test_bug1041626.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug1042436.xul b/js/xpconnect/tests/chrome/test_bug1042436.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug1042436.xul
rename to js/xpconnect/tests/chrome/test_bug1042436.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug1050049.html b/js/xpconnect/tests/chrome/test_bug1050049.html
deleted file mode 100644
index 74b349b4c1..0000000000
--- a/js/xpconnect/tests/chrome/test_bug1050049.html
+++ /dev/null
@@ -1,56 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<!--
-https://bugzilla.mozilla.org/show_bug.cgi?id=1050049
--->
-<head>
-  <meta charset="utf-8">
-  <title>Test for Bug 1050049</title>
-  <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
-  <link rel="stylesheet" type="text/css" href="chrome://global/skin"/>
-  <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
-  <script type="application/javascript">
-
-  /** Test for Bug 1050049 **/
-  SimpleTest.waitForExplicitFinish();
-
-  var regularBindingURI = window.location.toString().replace("test_bug1050049.html", "file_bug1050049.xml") + "#regularChromeBinding";
-  var whitelistedBindingURI = window.location.toString().replace("test_bug1050049.html", "file_bug1050049.xml") + "#whitelistedChromeBinding";
-
-  function testApplyBinding(doc, bindingURI, expectBind) {
-    var d = doc.createElement('div');
-    doc.body.appendChild(d);
-    d.style.MozBinding = "url(" + bindingURI + ")";
-
-    return new Promise(function(resolve, reject) {
-      // Wait two ticks of the refresh driver for the binding to be applied.
-      function onceBindingWouldBeApplied() {
-        is(!!doc.getAnonymousNodes(d), expectBind, "Binding " + (expectBind ? "should" : "shouldn't") +
-                                                   " be applied: " + bindingURI + ", " + doc.location);
-        resolve();
-      }
-      window.requestAnimationFrame(function() { window.requestAnimationFrame(onceBindingWouldBeApplied); });
-    });
-  }
-
-  function go() {
-    testApplyBinding(document, regularBindingURI, true)
-      .then(testApplyBinding.bind(null, window[0].document, regularBindingURI, false))
-      .then(testApplyBinding.bind(null, document, whitelistedBindingURI, true))
-      .then(testApplyBinding.bind(null, window[0].document, whitelistedBindingURI, true))
-      .then(SimpleTest.finish.bind(SimpleTest));
-  }
-
-  </script>
-</head>
-<body>
-<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1050049">Mozilla Bug 1050049</a>
-<p id="display"></p>
-<div id="content" style="display: none">
-
-</div>
-<pre id="test">
-</pre>
-<iframe onload="go();" src="http://example.org/tests/js/xpconnect/tests/mochitest/file_empty.html"></iframe>
-</body>
-</html>
diff --git a/js/xpconnect/tests/chrome/test_bug1092477.xul b/js/xpconnect/tests/chrome/test_bug1092477.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug1092477.xul
rename to js/xpconnect/tests/chrome/test_bug1092477.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug1281071.xul b/js/xpconnect/tests/chrome/test_bug1281071.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug1281071.xul
rename to js/xpconnect/tests/chrome/test_bug1281071.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug1390159.xul b/js/xpconnect/tests/chrome/test_bug1390159.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug1390159.xul
rename to js/xpconnect/tests/chrome/test_bug1390159.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug361111.xul b/js/xpconnect/tests/chrome/test_bug361111.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug361111.xul
rename to js/xpconnect/tests/chrome/test_bug361111.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug448587.xul b/js/xpconnect/tests/chrome/test_bug448587.xhtml
similarity index 94%
rename from js/xpconnect/tests/chrome/test_bug448587.xul
rename to js/xpconnect/tests/chrome/test_bug448587.xhtml
index 7d37e9f19c..cedab9ebbd 100644
--- a/js/xpconnect/tests/chrome/test_bug448587.xul
+++ b/js/xpconnect/tests/chrome/test_bug448587.xhtml
@@ -18,7 +18,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=448587.xul
   <script type="application/javascript">
   <![CDATA[
 
-  // Bonus test - collaborate with test_bug361111.xul to make sure that
+  // Bonus test - collaborate with test_bug361111.xhtml to make sure that
   // flushPrefEnv is appropriately called.
   ok(!SpecialPowers.Services.prefs.prefHasUserValue('testing.some_arbitrary_pref'),
      "Pref shouldn't carry over from previous test!");
diff --git a/js/xpconnect/tests/chrome/test_bug484459.xul b/js/xpconnect/tests/chrome/test_bug484459.xhtml
similarity index 97%
rename from js/xpconnect/tests/chrome/test_bug484459.xul
rename to js/xpconnect/tests/chrome/test_bug484459.xhtml
index cc042723fe..59f2f4ea60 100644
--- a/js/xpconnect/tests/chrome/test_bug484459.xul
+++ b/js/xpconnect/tests/chrome/test_bug484459.xhtml
@@ -21,7 +21,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=484459
   <!-- test code goes here -->
   <script type="application/javascript"><![CDATA[
     SimpleTest.waitForExplicitFinish();
-    var url = "chrome://mochitests/content/chrome/js/xpconnect/tests/chrome/test_bug484459.xul";
+    var url = "chrome://mochitests/content/chrome/js/xpconnect/tests/chrome/test_bug484459.xhtml";
     function go() {
       var w = $('ifr').contentWindow.wrappedJSObject;
       var sandbox = new Cu.Sandbox(w);
diff --git a/js/xpconnect/tests/chrome/test_bug500931.xul b/js/xpconnect/tests/chrome/test_bug500931.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug500931.xul
rename to js/xpconnect/tests/chrome/test_bug500931.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug503926.xul b/js/xpconnect/tests/chrome/test_bug503926.xhtml
similarity index 95%
rename from js/xpconnect/tests/chrome/test_bug503926.xul
rename to js/xpconnect/tests/chrome/test_bug503926.xhtml
index 93a25bba99..a25f8fcffa 100644
--- a/js/xpconnect/tests/chrome/test_bug503926.xul
+++ b/js/xpconnect/tests/chrome/test_bug503926.xhtml
@@ -13,7 +13,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=503926
   <a href="https://bugzilla.mozilla.org/show_bug.cgi?id=503926"
      target="_blank">Mozilla Bug 503926</a>
 
-  <iframe id="ifr" type="content" onload="loaded()" src="bug503926.xul#iframe"/>
+  <iframe id="ifr" type="content" onload="loaded()" src="bug503926.xhtml#iframe"/>
   <iframe id="ifrContent" type="content" onload="loaded()" src="http://example.org/tests/js/xpconnect/tests/mochitest/file_empty.html"/>
   </body>
 
@@ -47,7 +47,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=503926
     ok(!contentWin.passed, "untrusted QI should not be called");
 
     // Try with a dialog.
-    openDialog("bug503926.xul", "chromeDialog", "modal");
+    openDialog("bug503926.xhtml", "chromeDialog", "modal");
     SimpleTest.finish();
   }
 
diff --git a/js/xpconnect/tests/chrome/test_bug533596.xul b/js/xpconnect/tests/chrome/test_bug533596.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug533596.xul
rename to js/xpconnect/tests/chrome/test_bug533596.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug571849.xul b/js/xpconnect/tests/chrome/test_bug571849.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug571849.xul
rename to js/xpconnect/tests/chrome/test_bug571849.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug596580.xul b/js/xpconnect/tests/chrome/test_bug596580.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug596580.xul
rename to js/xpconnect/tests/chrome/test_bug596580.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug610390.xul b/js/xpconnect/tests/chrome/test_bug610390.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug610390.xul
rename to js/xpconnect/tests/chrome/test_bug610390.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug614757.xul b/js/xpconnect/tests/chrome/test_bug614757.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug614757.xul
rename to js/xpconnect/tests/chrome/test_bug614757.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug616992.xul b/js/xpconnect/tests/chrome/test_bug616992.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug616992.xul
rename to js/xpconnect/tests/chrome/test_bug616992.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug618176.xul b/js/xpconnect/tests/chrome/test_bug618176.xhtml
similarity index 94%
rename from js/xpconnect/tests/chrome/test_bug618176.xul
rename to js/xpconnect/tests/chrome/test_bug618176.xhtml
index 3dd20d948a..b3e9148a72 100644
--- a/js/xpconnect/tests/chrome/test_bug618176.xul
+++ b/js/xpconnect/tests/chrome/test_bug618176.xhtml
@@ -24,7 +24,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=618176
   }
 
   addLoadEvent(function() {
-    window.open("file_bug618176.xul", "", "chrome");
+    window.open("file_bug618176.xhtml", "", "chrome");
   });
   ]]></script>
 </window>
diff --git a/js/xpconnect/tests/chrome/test_bug654370.xul b/js/xpconnect/tests/chrome/test_bug654370.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug654370.xul
rename to js/xpconnect/tests/chrome/test_bug654370.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug658560.xul b/js/xpconnect/tests/chrome/test_bug658560.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug658560.xul
rename to js/xpconnect/tests/chrome/test_bug658560.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug658909.xul b/js/xpconnect/tests/chrome/test_bug658909.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug658909.xul
rename to js/xpconnect/tests/chrome/test_bug658909.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug664689.xul b/js/xpconnect/tests/chrome/test_bug664689.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug664689.xul
rename to js/xpconnect/tests/chrome/test_bug664689.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug679861.xul b/js/xpconnect/tests/chrome/test_bug679861.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug679861.xul
rename to js/xpconnect/tests/chrome/test_bug679861.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug706301.xul b/js/xpconnect/tests/chrome/test_bug706301.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug706301.xul
rename to js/xpconnect/tests/chrome/test_bug706301.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug720619.xul b/js/xpconnect/tests/chrome/test_bug720619.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug720619.xul
rename to js/xpconnect/tests/chrome/test_bug720619.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug726949.xul b/js/xpconnect/tests/chrome/test_bug726949.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug726949.xul
rename to js/xpconnect/tests/chrome/test_bug726949.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug732665.xul b/js/xpconnect/tests/chrome/test_bug732665.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug732665.xul
rename to js/xpconnect/tests/chrome/test_bug732665.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug738244.xul b/js/xpconnect/tests/chrome/test_bug738244.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug738244.xul
rename to js/xpconnect/tests/chrome/test_bug738244.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug743843.xul b/js/xpconnect/tests/chrome/test_bug743843.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug743843.xul
rename to js/xpconnect/tests/chrome/test_bug743843.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug760076.xul b/js/xpconnect/tests/chrome/test_bug760076.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug760076.xul
rename to js/xpconnect/tests/chrome/test_bug760076.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug763343.xul b/js/xpconnect/tests/chrome/test_bug763343.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug763343.xul
rename to js/xpconnect/tests/chrome/test_bug763343.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug771429.xul b/js/xpconnect/tests/chrome/test_bug771429.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug771429.xul
rename to js/xpconnect/tests/chrome/test_bug771429.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug773962.xul b/js/xpconnect/tests/chrome/test_bug773962.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug773962.xul
rename to js/xpconnect/tests/chrome/test_bug773962.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug792280.xul b/js/xpconnect/tests/chrome/test_bug792280.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug792280.xul
rename to js/xpconnect/tests/chrome/test_bug792280.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug793433.xul b/js/xpconnect/tests/chrome/test_bug793433.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug793433.xul
rename to js/xpconnect/tests/chrome/test_bug793433.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug795275.xul b/js/xpconnect/tests/chrome/test_bug795275.xhtml
similarity index 94%
rename from js/xpconnect/tests/chrome/test_bug795275.xul
rename to js/xpconnect/tests/chrome/test_bug795275.xhtml
index 2786ca1839..1e87c7984c 100644
--- a/js/xpconnect/tests/chrome/test_bug795275.xul
+++ b/js/xpconnect/tests/chrome/test_bug795275.xhtml
@@ -65,8 +65,6 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=795275
     getWin('frame2').touchInterfaces();
     getWin('frame4').touchComponents();
     getWin('frame4').touchInterfaces();
-    // This should warn twice.
-    getWin('frame5').touchViaXBL();
 
     // Warnings are dispatched async, so stick ourselves at the end of the event
     // queue.
@@ -75,7 +73,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=795275
 
   function done() {
     gConsoleService.unregisterListener(gListener);
-    is(gWarnings, 5, "Got the right number of warnings");
+    is(gWarnings, 3, "Got the right number of warnings");
     SimpleTest.finish();
   }
 
@@ -86,6 +84,5 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=795275
   <iframe id="frame2"/>
   <iframe id="frame3"/>
   <iframe id="frame4"/>
-  <iframe id="frame5"/>
 
 </window>
diff --git a/js/xpconnect/tests/chrome/test_bug799348.xul b/js/xpconnect/tests/chrome/test_bug799348.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug799348.xul
rename to js/xpconnect/tests/chrome/test_bug799348.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug801241.xul b/js/xpconnect/tests/chrome/test_bug801241.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug801241.xul
rename to js/xpconnect/tests/chrome/test_bug801241.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug812415.xul b/js/xpconnect/tests/chrome/test_bug812415.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug812415.xul
rename to js/xpconnect/tests/chrome/test_bug812415.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug853283.xul b/js/xpconnect/tests/chrome/test_bug853283.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug853283.xul
rename to js/xpconnect/tests/chrome/test_bug853283.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug853571.xul b/js/xpconnect/tests/chrome/test_bug853571.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug853571.xul
rename to js/xpconnect/tests/chrome/test_bug853571.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug858101.xul b/js/xpconnect/tests/chrome/test_bug858101.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug858101.xul
rename to js/xpconnect/tests/chrome/test_bug858101.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug860494.xul b/js/xpconnect/tests/chrome/test_bug860494.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug860494.xul
rename to js/xpconnect/tests/chrome/test_bug860494.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug865948.xul b/js/xpconnect/tests/chrome/test_bug865948.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug865948.xul
rename to js/xpconnect/tests/chrome/test_bug865948.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug866823.xul b/js/xpconnect/tests/chrome/test_bug866823.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug866823.xul
rename to js/xpconnect/tests/chrome/test_bug866823.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug895340.xul b/js/xpconnect/tests/chrome/test_bug895340.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug895340.xul
rename to js/xpconnect/tests/chrome/test_bug895340.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug932906.xul b/js/xpconnect/tests/chrome/test_bug932906.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug932906.xul
rename to js/xpconnect/tests/chrome/test_bug932906.xhtml
diff --git a/js/xpconnect/tests/chrome/test_bug996069.xul b/js/xpconnect/tests/chrome/test_bug996069.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_bug996069.xul
rename to js/xpconnect/tests/chrome/test_bug996069.xhtml
diff --git a/js/xpconnect/tests/chrome/test_chrometoSource.xul b/js/xpconnect/tests/chrome/test_chrometoSource.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_chrometoSource.xul
rename to js/xpconnect/tests/chrome/test_chrometoSource.xhtml
diff --git a/js/xpconnect/tests/chrome/test_cloneInto.xul b/js/xpconnect/tests/chrome/test_cloneInto.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_cloneInto.xul
rename to js/xpconnect/tests/chrome/test_cloneInto.xhtml
diff --git a/js/xpconnect/tests/chrome/test_cows.xul b/js/xpconnect/tests/chrome/test_cows.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_cows.xul
rename to js/xpconnect/tests/chrome/test_cows.xhtml
diff --git a/js/xpconnect/tests/chrome/test_discardSystemSource.xul b/js/xpconnect/tests/chrome/test_discardSystemSource.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_discardSystemSource.xul
rename to js/xpconnect/tests/chrome/test_discardSystemSource.xhtml
diff --git a/js/xpconnect/tests/chrome/test_documentdomain.xul b/js/xpconnect/tests/chrome/test_documentdomain.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_documentdomain.xul
rename to js/xpconnect/tests/chrome/test_documentdomain.xhtml
diff --git a/js/xpconnect/tests/chrome/test_doublewrappedcompartments.xul b/js/xpconnect/tests/chrome/test_doublewrappedcompartments.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_doublewrappedcompartments.xul
rename to js/xpconnect/tests/chrome/test_doublewrappedcompartments.xhtml
diff --git a/js/xpconnect/tests/chrome/test_evalInSandbox.xul b/js/xpconnect/tests/chrome/test_evalInSandbox.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_evalInSandbox.xul
rename to js/xpconnect/tests/chrome/test_evalInSandbox.xhtml
diff --git a/js/xpconnect/tests/chrome/test_evalInWindow.xul b/js/xpconnect/tests/chrome/test_evalInWindow.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_evalInWindow.xul
rename to js/xpconnect/tests/chrome/test_evalInWindow.xhtml
diff --git a/js/xpconnect/tests/chrome/test_exnstack.xul b/js/xpconnect/tests/chrome/test_exnstack.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_exnstack.xul
rename to js/xpconnect/tests/chrome/test_exnstack.xhtml
diff --git a/js/xpconnect/tests/chrome/test_expandosharing.xul b/js/xpconnect/tests/chrome/test_expandosharing.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_expandosharing.xul
rename to js/xpconnect/tests/chrome/test_expandosharing.xhtml
diff --git a/js/xpconnect/tests/chrome/test_exposeInDerived.xul b/js/xpconnect/tests/chrome/test_exposeInDerived.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_exposeInDerived.xul
rename to js/xpconnect/tests/chrome/test_exposeInDerived.xhtml
diff --git a/js/xpconnect/tests/chrome/test_localstorage_with_nsEp.xul b/js/xpconnect/tests/chrome/test_localstorage_with_nsEp.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_localstorage_with_nsEp.xul
rename to js/xpconnect/tests/chrome/test_localstorage_with_nsEp.xhtml
diff --git a/js/xpconnect/tests/chrome/test_matches.xul b/js/xpconnect/tests/chrome/test_matches.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_matches.xul
rename to js/xpconnect/tests/chrome/test_matches.xhtml
diff --git a/js/xpconnect/tests/chrome/test_nodelists.xul b/js/xpconnect/tests/chrome/test_nodelists.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_nodelists.xul
rename to js/xpconnect/tests/chrome/test_nodelists.xhtml
diff --git a/js/xpconnect/tests/chrome/test_precisegc.xul b/js/xpconnect/tests/chrome/test_precisegc.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_precisegc.xul
rename to js/xpconnect/tests/chrome/test_precisegc.xhtml
diff --git a/js/xpconnect/tests/chrome/test_sandboxImport.xul b/js/xpconnect/tests/chrome/test_sandboxImport.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_sandboxImport.xul
rename to js/xpconnect/tests/chrome/test_sandboxImport.xhtml
diff --git a/js/xpconnect/tests/chrome/test_scriptSettings.xul b/js/xpconnect/tests/chrome/test_scriptSettings.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_scriptSettings.xul
rename to js/xpconnect/tests/chrome/test_scriptSettings.xhtml
diff --git a/js/xpconnect/tests/chrome/test_weakmap_keys_preserved.xul b/js/xpconnect/tests/chrome/test_weakmap_keys_preserved.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_weakmap_keys_preserved.xul
rename to js/xpconnect/tests/chrome/test_weakmap_keys_preserved.xhtml
diff --git a/js/xpconnect/tests/chrome/test_weakmap_keys_preserved2.xul b/js/xpconnect/tests/chrome/test_weakmap_keys_preserved2.xhtml
similarity index 92%
rename from js/xpconnect/tests/chrome/test_weakmap_keys_preserved2.xul
rename to js/xpconnect/tests/chrome/test_weakmap_keys_preserved2.xhtml
index 8ffef02398..d93bc2d30c 100644
--- a/js/xpconnect/tests/chrome/test_weakmap_keys_preserved2.xul
+++ b/js/xpconnect/tests/chrome/test_weakmap_keys_preserved2.xhtml
@@ -27,12 +27,12 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=673468
 
   let wrappers_as_keys_test = function () {
     let e = new MessageEvent("foo", { bubbles: false, cancellable: false,
-                                      data: { dummy: document.createElement("foo") }});
+                                      data: { dummy: document.createXULElement("foo") }});
     window.eeeevent = e;
 
     let live_dom = e.data.dummy;
-    let dead_dom = document.createElement("div");
-    let dead_child = document.createElement("div");
+    let dead_dom = document.createElementNS("http://www.w3.org/1999/xhtml", "div");
+    let dead_child = document.createElementNS("http://www.w3.org/1999/xhtml", "div");
     dead_dom.appendChild(dead_child);
     is(dead_dom.children.length, 1, "children have wrong length");
     let wrappee = new Object();
diff --git a/js/xpconnect/tests/chrome/test_weakref.xul b/js/xpconnect/tests/chrome/test_weakref.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_weakref.xul
rename to js/xpconnect/tests/chrome/test_weakref.xhtml
diff --git a/js/xpconnect/tests/chrome/test_wrappers.xul b/js/xpconnect/tests/chrome/test_wrappers.xhtml
similarity index 93%
rename from js/xpconnect/tests/chrome/test_wrappers.xul
rename to js/xpconnect/tests/chrome/test_wrappers.xhtml
index 6f59f2383e..32308eb72b 100644
--- a/js/xpconnect/tests/chrome/test_wrappers.xul
+++ b/js/xpconnect/tests/chrome/test_wrappers.xhtml
@@ -72,14 +72,6 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=500931
    // Test getter/setter lookup on Xray wrappers.
    ok(Object.prototype.__lookupGetter__.call(win.document, 'title'), 'found getter on document');
    ok(Object.prototype.__lookupGetter__.call(win.document, 'title'), 'found getter on document');
-
-   // Test QI on new dom bindings.
-   try {
-     var QIed = win.QueryInterface(Ci.nsIClassInfo);
-     ok(false, "Should throw for new binding objects not having classinfo");
-   } catch(e) {
-     is(e.name, "NS_NOINTERFACE", "Threw while QI-ing on wrapper");
-   }
   }
 
   SimpleTest.waitForExplicitFinish();
diff --git a/js/xpconnect/tests/chrome/test_xrayToJS.xul b/js/xpconnect/tests/chrome/test_xrayToJS.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_xrayToJS.xul
rename to js/xpconnect/tests/chrome/test_xrayToJS.xhtml
diff --git a/js/xpconnect/tests/chrome/test_xrayic.xul b/js/xpconnect/tests/chrome/test_xrayic.xhtml
similarity index 100%
rename from js/xpconnect/tests/chrome/test_xrayic.xul
rename to js/xpconnect/tests/chrome/test_xrayic.xhtml
diff --git a/js/xpconnect/tests/mochitest/file_bug795275.html b/js/xpconnect/tests/mochitest/file_bug795275.html
index 95e9f2a8ea..c3886b8ba8 100644
--- a/js/xpconnect/tests/mochitest/file_bug795275.html
+++ b/js/xpconnect/tests/mochitest/file_bug795275.html
@@ -1,10 +1,5 @@
 <html>
 <head>
-<style>
-  .bound {
-    -moz-binding: url(file_bug795275.xml#xbltest);
-  }
-</style>
 <script type="application/javascript">
   function touchComponents() {
     Components;
@@ -12,17 +7,8 @@
   function touchInterfaces() {
     Components.interfaces;
   }
-
-  function touchViaXBL() {
-    // Make sure none of this warns.
-    var div = document.getElementById('dummy');
-    div.testProp;
-    div.testMethod();
-  }
-
 </script>
 </head>
 <body>
-<div id="dummy" class="bound"></div>
 </body>
 </html>
diff --git a/js/xpconnect/tests/mochitest/file_bug795275.xml b/js/xpconnect/tests/mochitest/file_bug795275.xml
deleted file mode 100644
index f9e5e60f58..0000000000
--- a/js/xpconnect/tests/mochitest/file_bug795275.xml
+++ /dev/null
@@ -1,19 +0,0 @@
-<?xml version="1.0"?>
-<bindings id="xbltestBindings" xmlns="http://www.mozilla.org/xbl"
-          xmlns:html="http://www.w3.org/1999/xhtml">
-<binding id="xbltest">
-<implementation>
-<method name="testMethod" exposeToUntrustedContent="true">
-<body>
-  Components.interfaces;
-</body>
-</method>
-<property name="testProp" readonly="true"
-          onget="Components; return 3;"
-          exposeToUntrustedContent="true" />
-<constructor>
-  var foo = Components;
-</constructor>
-</implementation>
-</binding>
-</bindings>
diff --git a/js/xpconnect/tests/mochitest/mochitest.ini b/js/xpconnect/tests/mochitest/mochitest.ini
index a0f855e699..479c835343 100644
--- a/js/xpconnect/tests/mochitest/mochitest.ini
+++ b/js/xpconnect/tests/mochitest/mochitest.ini
@@ -20,7 +20,6 @@ support-files =
   file_bug781476.html
   file_bug789713.html
   file_bug795275.html
-  file_bug795275.xml
   file_bug799348.html
   file_bug802557.html
   file_bug860494.html
diff --git a/js/xpconnect/tests/mochitest/test_bug912322.html b/js/xpconnect/tests/mochitest/test_bug912322.html
index e71e1d6cfd..377b9bc66f 100644
--- a/js/xpconnect/tests/mochitest/test_bug912322.html
+++ b/js/xpconnect/tests/mochitest/test_bug912322.html
@@ -10,14 +10,6 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=912322
   <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
   <script type="application/javascript">
 
-  /** Test that XBL functions aren't exposed to the web. **/
-  funs = ['getAnonymousNodes', 'getAnonymousElementByAttribute',
-          'getBindingParent', 'loadBindingDocument'];
-  for (var f of funs) {
-    ok(!(f in document), f + " should not be available to content");
-    ok(f in SpecialPowers.wrap(document), f + " should be available to chrome via Xray");
-  }
-
   var {AppConstants} = SpecialPowers.Cu.import("resource://gre/modules/AppConstants.jsm", {});
   // Test window.controllers.
   if (AppConstants.RELEASE_OR_BETA) {
diff --git a/js/xpconnect/tests/unit/test_structuredClone.js b/js/xpconnect/tests/unit/test_structuredClone.js
new file mode 100644
index 0000000000..6b9b2d776a
--- /dev/null
+++ b/js/xpconnect/tests/unit/test_structuredClone.js
@@ -0,0 +1,25 @@
+function run_test() {
+  var sb = new Cu.Sandbox('http://www.example.com',
+                          { wantGlobalProperties: ["structuredClone"] });
+
+  sb.equal = equal;
+
+  sb.testing =  Components.utils.cloneInto({xyz: 123}, sb);
+  Cu.evalInSandbox(`
+    equal(structuredClone("abc"), "abc");
+
+    var obj = {a: 1};
+    obj.self = obj;
+    var clone = structuredClone(obj);
+    equal(clone.a, 1);
+    equal(clone.self, clone);
+
+    var ab = new ArrayBuffer(1);
+    clone = structuredClone(ab, {transfer: [ab]});
+    equal(clone.byteLength, 1);
+    equal(ab.byteLength, 0);
+
+    clone = structuredClone(testing);
+    equal(clone.xyz, 123);
+  `, sb);
+}
diff --git a/js/xpconnect/tests/unit/xpcshell.ini b/js/xpconnect/tests/unit/xpcshell.ini
index f82f398285..5cf2396738 100644
--- a/js/xpconnect/tests/unit/xpcshell.ini
+++ b/js/xpconnect/tests/unit/xpcshell.ini
@@ -123,6 +123,7 @@ head = head_ongc.js
 [test_css.js]
 [test_rtcIdentityProvider.js]
 [test_sandbox_atob.js]
+[test_structuredClone.js]
 [test_isProxy.js]
 [test_js_memory_telemetry.js]
 [test_getObjectPrincipal.js]
diff --git a/js/xpconnect/wrappers/WrapperFactory.cpp b/js/xpconnect/wrappers/WrapperFactory.cpp
index 34c9549f7c..9ec03fc535 100644
--- a/js/xpconnect/wrappers/WrapperFactory.cpp
+++ b/js/xpconnect/wrappers/WrapperFactory.cpp
@@ -439,16 +439,6 @@ static const Wrapper* SelectWrapper(bool securityWrapper, XrayType xrayType,
 
   // There's never any reason to expose other objects to non-subsuming actors.
   // Just use an opaque wrapper in these cases.
-  //
-  // In general, we don't want opaque function wrappers to be callable.
-  // But in the case of XBL, we rely on content being able to invoke
-  // functions exposed from the XBL scope. We could remove this exception,
-  // if needed, by using ExportFunction to generate the content-side
-  // representations of XBL methods.
-  if (xrayType == XrayForJSObject && IsInContentXBLScope(obj)) {
-    return &FilteringWrapper<CrossCompartmentSecurityWrapper,
-                             OpaqueWithCall>::singleton;
-  }
   return &FilteringWrapper<CrossCompartmentSecurityWrapper, Opaque>::singleton;
 }