Add m-esr52 at 52.6.0

1 files changed, 1435 insertions, 0 deletions

diff --git a/js/src/jsfriendapi.cpp b/js/src/jsfriendapi.cpp
new file mode 100644
index 0000000000..595a214102
--- /dev/null
+++ b/js/src/jsfriendapi.cpp
@@ -0,0 +1,1435 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * 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 "jsfriendapi.h"
+
+#include "mozilla/PodOperations.h"
+
+#include <stdint.h>
+
+#include "jscntxt.h"
+#include "jscompartment.h"
+#include "jsgc.h"
+#include "jsobj.h"
+#include "jsprf.h"
+#include "jswatchpoint.h"
+#include "jsweakmap.h"
+#include "jswrapper.h"
+
+#include "builtin/Promise.h"
+#include "builtin/TestingFunctions.h"
+#include "js/Proxy.h"
+#include "proxy/DeadObjectProxy.h"
+#include "vm/ArgumentsObject.h"
+#include "vm/Time.h"
+#include "vm/WrapperObject.h"
+
+#include "jsobjinlines.h"
+#include "jsscriptinlines.h"
+
+#include "vm/EnvironmentObject-inl.h"
+#include "vm/NativeObject-inl.h"
+
+using namespace js;
+
+using mozilla::Move;
+using mozilla::PodArrayZero;
+
+js::ContextFriendFields::ContextFriendFields(bool isJSContext)
+  : JS::RootingContext(isJSContext),
+    compartment_(nullptr), zone_(nullptr)
+{
+    PodArrayZero(nativeStackLimit);
+#if JS_STACK_GROWTH_DIRECTION > 0
+    for (int i=0; i<StackKindCount; i++)
+        nativeStackLimit[i] = UINTPTR_MAX;
+#endif
+}
+
+JS_FRIEND_API(void)
+js::SetSourceHook(JSContext* cx, mozilla::UniquePtr<SourceHook> hook)
+{
+    cx->sourceHook = Move(hook);
+}
+
+JS_FRIEND_API(mozilla::UniquePtr<SourceHook>)
+js::ForgetSourceHook(JSContext* cx)
+{
+    return Move(cx->sourceHook);
+}
+
+JS_FRIEND_API(void)
+JS_SetGrayGCRootsTracer(JSContext* cx, JSTraceDataOp traceOp, void* data)
+{
+    cx->gc.setGrayRootsTracer(traceOp, data);
+}
+
+JS_FRIEND_API(JSObject*)
+JS_FindCompilationScope(JSContext* cx, HandleObject objArg)
+{
+    RootedObject obj(cx, objArg);
+
+    /*
+     * We unwrap wrappers here. This is a little weird, but it's what's being
+     * asked of us.
+     */
+    if (obj->is<WrapperObject>())
+        obj = UncheckedUnwrap(obj);
+
+    /*
+     * Get the Window if `obj` is a WindowProxy so that we compile in the
+     * correct (global) scope.
+     */
+    return ToWindowIfWindowProxy(obj);
+}
+
+JS_FRIEND_API(JSFunction*)
+JS_GetObjectFunction(JSObject* obj)
+{
+    if (obj->is<JSFunction>())
+        return &obj->as<JSFunction>();
+    return nullptr;
+}
+
+JS_FRIEND_API(bool)
+JS_SplicePrototype(JSContext* cx, HandleObject obj, HandleObject proto)
+{
+    /*
+     * Change the prototype of an object which hasn't been used anywhere
+     * and does not share its type with another object. Unlike JS_SetPrototype,
+     * does not nuke type information for the object.
+     */
+    CHECK_REQUEST(cx);
+
+    if (!obj->isSingleton()) {
+        /*
+         * We can see non-singleton objects when trying to splice prototypes
+         * due to mutable __proto__ (ugh).
+         */
+        return JS_SetPrototype(cx, obj, proto);
+    }
+
+    Rooted<TaggedProto> tagged(cx, TaggedProto(proto));
+    return obj->splicePrototype(cx, obj->getClass(), tagged);
+}
+
+JS_FRIEND_API(JSObject*)
+JS_NewObjectWithUniqueType(JSContext* cx, const JSClass* clasp, HandleObject proto)
+{
+    /*
+     * Create our object with a null proto and then splice in the correct proto
+     * after we setSingleton, so that we don't pollute the default
+     * ObjectGroup attached to our proto with information about our object, since
+     * we're not going to be using that ObjectGroup anyway.
+     */
+    RootedObject obj(cx, NewObjectWithGivenProto(cx, (const js::Class*)clasp, nullptr,
+                                                 SingletonObject));
+    if (!obj)
+        return nullptr;
+    if (!JS_SplicePrototype(cx, obj, proto))
+        return nullptr;
+    return obj;
+}
+
+JS_FRIEND_API(JSObject*)
+JS_NewObjectWithoutMetadata(JSContext* cx, const JSClass* clasp, JS::Handle<JSObject*> proto)
+{
+    AutoSuppressAllocationMetadataBuilder suppressMetadata(cx);
+    return JS_NewObjectWithGivenProto(cx, clasp, proto);
+}
+
+JS_FRIEND_API(bool)
+JS_GetIsSecureContext(JSCompartment* compartment)
+{
+    return compartment->creationOptions().secureContext();
+}
+
+JS_FRIEND_API(JSPrincipals*)
+JS_GetCompartmentPrincipals(JSCompartment* compartment)
+{
+    return compartment->principals();
+}
+
+JS_FRIEND_API(void)
+JS_SetCompartmentPrincipals(JSCompartment* compartment, JSPrincipals* principals)
+{
+    // Short circuit if there's no change.
+    if (principals == compartment->principals())
+        return;
+
+    // Any compartment with the trusted principals -- and there can be
+    // multiple -- is a system compartment.
+    const JSPrincipals* trusted = compartment->runtimeFromMainThread()->trustedPrincipals();
+    bool isSystem = principals && principals == trusted;
+
+    // Clear out the old principals, if any.
+    if (compartment->principals()) {
+        JS_DropPrincipals(compartment->contextFromMainThread(), compartment->principals());
+        compartment->setPrincipals(nullptr);
+        // We'd like to assert that our new principals is always same-origin
+        // with the old one, but JSPrincipals doesn't give us a way to do that.
+        // But we can at least assert that we're not switching between system
+        // and non-system.
+        MOZ_ASSERT(compartment->isSystem() == isSystem);
+    }
+
+    // Set up the new principals.
+    if (principals) {
+        JS_HoldPrincipals(principals);
+        compartment->setPrincipals(principals);
+    }
+
+    // Update the system flag.
+    compartment->setIsSystem(isSystem);
+}
+
+JS_FRIEND_API(JSPrincipals*)
+JS_GetScriptPrincipals(JSScript* script)
+{
+    return script->principals();
+}
+
+JS_FRIEND_API(bool)
+JS_ScriptHasMutedErrors(JSScript* script)
+{
+    return script->mutedErrors();
+}
+
+JS_FRIEND_API(bool)
+JS_WrapPropertyDescriptor(JSContext* cx, JS::MutableHandle<js::PropertyDescriptor> desc)
+{
+    return cx->compartment()->wrap(cx, desc);
+}
+
+JS_FRIEND_API(void)
+JS_TraceShapeCycleCollectorChildren(JS::CallbackTracer* trc, JS::GCCellPtr shape)
+{
+    MOZ_ASSERT(shape.is<Shape>());
+    TraceCycleCollectorChildren(trc, &shape.as<Shape>());
+}
+
+JS_FRIEND_API(void)
+JS_TraceObjectGroupCycleCollectorChildren(JS::CallbackTracer* trc, JS::GCCellPtr group)
+{
+    MOZ_ASSERT(group.is<ObjectGroup>());
+    TraceCycleCollectorChildren(trc, &group.as<ObjectGroup>());
+}
+
+static bool
+DefineHelpProperty(JSContext* cx, HandleObject obj, const char* prop, const char* value)
+{
+    RootedAtom atom(cx, Atomize(cx, value, strlen(value)));
+    if (!atom)
+        return false;
+    return JS_DefineProperty(cx, obj, prop, atom,
+                             JSPROP_READONLY | JSPROP_PERMANENT,
+                             JS_STUBGETTER, JS_STUBSETTER);
+}
+
+JS_FRIEND_API(bool)
+JS_DefineFunctionsWithHelp(JSContext* cx, HandleObject obj, const JSFunctionSpecWithHelp* fs)
+{
+    MOZ_ASSERT(!cx->runtime()->isAtomsCompartment(cx->compartment()));
+
+    CHECK_REQUEST(cx);
+    assertSameCompartment(cx, obj);
+    for (; fs->name; fs++) {
+        JSAtom* atom = Atomize(cx, fs->name, strlen(fs->name));
+        if (!atom)
+            return false;
+
+        Rooted<jsid> id(cx, AtomToId(atom));
+        RootedFunction fun(cx, DefineFunction(cx, obj, id, fs->call, fs->nargs, fs->flags));
+        if (!fun)
+            return false;
+
+        if (fs->jitInfo)
+            fun->setJitInfo(fs->jitInfo);
+
+        if (fs->usage) {
+            if (!DefineHelpProperty(cx, fun, "usage", fs->usage))
+                return false;
+        }
+
+        if (fs->help) {
+            if (!DefineHelpProperty(cx, fun, "help", fs->help))
+                return false;
+        }
+    }
+
+    return true;
+}
+
+JS_FRIEND_API(bool)
+js::GetBuiltinClass(JSContext* cx, HandleObject obj, ESClass* cls)
+{
+    if (MOZ_UNLIKELY(obj->is<ProxyObject>()))
+        return Proxy::getBuiltinClass(cx, obj, cls);
+
+    if (obj->is<PlainObject>() || obj->is<UnboxedPlainObject>())
+        *cls = ESClass::Object;
+    else if (obj->is<ArrayObject>() || obj->is<UnboxedArrayObject>())
+        *cls = ESClass::Array;
+    else if (obj->is<NumberObject>())
+        *cls = ESClass::Number;
+    else if (obj->is<StringObject>())
+        *cls = ESClass::String;
+    else if (obj->is<BooleanObject>())
+        *cls = ESClass::Boolean;
+    else if (obj->is<RegExpObject>())
+        *cls = ESClass::RegExp;
+    else if (obj->is<ArrayBufferObject>())
+        *cls = ESClass::ArrayBuffer;
+    else if (obj->is<SharedArrayBufferObject>())
+        *cls = ESClass::SharedArrayBuffer;
+    else if (obj->is<DateObject>())
+        *cls = ESClass::Date;
+    else if (obj->is<SetObject>())
+        *cls = ESClass::Set;
+    else if (obj->is<MapObject>())
+        *cls = ESClass::Map;
+    else if (obj->is<PromiseObject>())
+        *cls = ESClass::Promise;
+    else if (obj->is<MapIteratorObject>())
+        *cls = ESClass::MapIterator;
+    else if (obj->is<SetIteratorObject>())
+        *cls = ESClass::SetIterator;
+    else if (obj->is<ArgumentsObject>())
+        *cls = ESClass::Arguments;
+    else if (obj->is<ErrorObject>())
+        *cls = ESClass::Error;
+    else
+        *cls = ESClass::Other;
+
+    return true;
+}
+
+JS_FRIEND_API(const char*)
+js::ObjectClassName(JSContext* cx, HandleObject obj)
+{
+    return GetObjectClassName(cx, obj);
+}
+
+JS_FRIEND_API(JS::Zone*)
+js::GetCompartmentZone(JSCompartment* comp)
+{
+    return comp->zone();
+}
+
+JS_FRIEND_API(bool)
+js::IsSystemCompartment(JSCompartment* comp)
+{
+    return comp->isSystem();
+}
+
+JS_FRIEND_API(bool)
+js::IsSystemZone(Zone* zone)
+{
+    return zone->isSystem;
+}
+
+JS_FRIEND_API(bool)
+js::IsAtomsCompartment(JSCompartment* comp)
+{
+    return comp->runtimeFromAnyThread()->isAtomsCompartment(comp);
+}
+
+JS_FRIEND_API(bool)
+js::IsAtomsZone(JS::Zone* zone)
+{
+    return zone->runtimeFromAnyThread()->isAtomsZone(zone);
+}
+
+JS_FRIEND_API(bool)
+js::IsFunctionObject(JSObject* obj)
+{
+    return obj->is<JSFunction>();
+}
+
+JS_FRIEND_API(JSObject*)
+js::GetGlobalForObjectCrossCompartment(JSObject* obj)
+{
+    return &obj->global();
+}
+
+JS_FRIEND_API(JSObject*)
+js::GetPrototypeNoProxy(JSObject* obj)
+{
+    MOZ_ASSERT(!obj->is<js::ProxyObject>());
+    return obj->staticPrototype();
+}
+
+JS_FRIEND_API(void)
+js::AssertSameCompartment(JSContext* cx, JSObject* obj)
+{
+    assertSameCompartment(cx, obj);
+}
+
+#ifdef DEBUG
+JS_FRIEND_API(void)
+js::AssertSameCompartment(JSObject* objA, JSObject* objB)
+{
+    MOZ_ASSERT(objA->compartment() == objB->compartment());
+}
+#endif
+
+JS_FRIEND_API(void)
+js::NotifyAnimationActivity(JSObject* obj)
+{
+    int64_t timeNow = PRMJ_Now();
+    obj->compartment()->lastAnimationTime = timeNow;
+    obj->runtimeFromMainThread()->lastAnimationTime = timeNow;
+}
+
+JS_FRIEND_API(uint32_t)
+js::GetObjectSlotSpan(JSObject* obj)
+{
+    return obj->as<NativeObject>().slotSpan();
+}
+
+JS_FRIEND_API(bool)
+js::IsObjectInContextCompartment(JSObject* obj, const JSContext* cx)
+{
+    return obj->compartment() == cx->compartment();
+}
+
+JS_FRIEND_API(bool)
+js::RunningWithTrustedPrincipals(JSContext* cx)
+{
+    return cx->runningWithTrustedPrincipals();
+}
+
+JS_FRIEND_API(JSFunction*)
+js::GetOutermostEnclosingFunctionOfScriptedCaller(JSContext* cx)
+{
+    ScriptFrameIter iter(cx);
+
+    // Skip eval frames.
+    while (!iter.done() && iter.isEvalFrame())
+        ++iter;
+
+    if (iter.done())
+        return nullptr;
+
+    if (!iter.isFunctionFrame())
+        return nullptr;
+
+    if (iter.compartment() != cx->compartment())
+        return nullptr;
+
+    RootedFunction curr(cx, iter.callee(cx));
+    for (ScopeIter si(curr->nonLazyScript()); si; si++) {
+        if (si.kind() == ScopeKind::Function)
+            curr = si.scope()->as<FunctionScope>().canonicalFunction();
+    }
+
+    assertSameCompartment(cx, curr);
+    return curr;
+}
+
+JS_FRIEND_API(JSFunction*)
+js::DefineFunctionWithReserved(JSContext* cx, JSObject* objArg, const char* name, JSNative call,
+                               unsigned nargs, unsigned attrs)
+{
+    RootedObject obj(cx, objArg);
+    MOZ_ASSERT(!cx->runtime()->isAtomsCompartment(cx->compartment()));
+    CHECK_REQUEST(cx);
+    assertSameCompartment(cx, obj);
+    JSAtom* atom = Atomize(cx, name, strlen(name));
+    if (!atom)
+        return nullptr;
+    Rooted<jsid> id(cx, AtomToId(atom));
+    return DefineFunction(cx, obj, id, call, nargs, attrs, gc::AllocKind::FUNCTION_EXTENDED);
+}
+
+JS_FRIEND_API(JSFunction*)
+js::NewFunctionWithReserved(JSContext* cx, JSNative native, unsigned nargs, unsigned flags,
+                            const char* name)
+{
+    MOZ_ASSERT(!cx->runtime()->isAtomsCompartment(cx->compartment()));
+
+    CHECK_REQUEST(cx);
+
+    RootedAtom atom(cx);
+    if (name) {
+        atom = Atomize(cx, name, strlen(name));
+        if (!atom)
+            return nullptr;
+    }
+
+    return (flags & JSFUN_CONSTRUCTOR) ?
+        NewNativeConstructor(cx, native, nargs, atom, gc::AllocKind::FUNCTION_EXTENDED) :
+        NewNativeFunction(cx, native, nargs, atom, gc::AllocKind::FUNCTION_EXTENDED);
+}
+
+JS_FRIEND_API(JSFunction*)
+js::NewFunctionByIdWithReserved(JSContext* cx, JSNative native, unsigned nargs, unsigned flags,
+                                jsid id)
+{
+    MOZ_ASSERT(JSID_IS_STRING(id));
+    MOZ_ASSERT(!cx->runtime()->isAtomsCompartment(cx->compartment()));
+    CHECK_REQUEST(cx);
+
+    RootedAtom atom(cx, JSID_TO_ATOM(id));
+    return (flags & JSFUN_CONSTRUCTOR) ?
+        NewNativeConstructor(cx, native, nargs, atom, gc::AllocKind::FUNCTION_EXTENDED) :
+        NewNativeFunction(cx, native, nargs, atom, gc::AllocKind::FUNCTION_EXTENDED);
+}
+
+JS_FRIEND_API(const Value&)
+js::GetFunctionNativeReserved(JSObject* fun, size_t which)
+{
+    MOZ_ASSERT(fun->as<JSFunction>().isNative());
+    return fun->as<JSFunction>().getExtendedSlot(which);
+}
+
+JS_FRIEND_API(void)
+js::SetFunctionNativeReserved(JSObject* fun, size_t which, const Value& val)
+{
+    MOZ_ASSERT(fun->as<JSFunction>().isNative());
+    MOZ_ASSERT_IF(val.isObject(), val.toObject().compartment() == fun->compartment());
+    fun->as<JSFunction>().setExtendedSlot(which, val);
+}
+
+JS_FRIEND_API(bool)
+js::FunctionHasNativeReserved(JSObject* fun)
+{
+    MOZ_ASSERT(fun->as<JSFunction>().isNative());
+    return fun->as<JSFunction>().isExtended();
+}
+
+JS_FRIEND_API(bool)
+js::GetObjectProto(JSContext* cx, JS::Handle<JSObject*> obj, JS::MutableHandle<JSObject*> proto)
+{
+    if (IsProxy(obj))
+        return JS_GetPrototype(cx, obj, proto);
+
+    proto.set(reinterpret_cast<const shadow::Object*>(obj.get())->group->proto);
+    return true;
+}
+
+JS_FRIEND_API(JSObject*)
+js::GetStaticPrototype(JSObject* obj)
+{
+    MOZ_ASSERT(obj->hasStaticPrototype());
+    return obj->staticPrototype();
+}
+
+JS_FRIEND_API(bool)
+js::GetOriginalEval(JSContext* cx, HandleObject scope, MutableHandleObject eval)
+{
+    assertSameCompartment(cx, scope);
+    Rooted<GlobalObject*> global(cx, &scope->global());
+    return GlobalObject::getOrCreateEval(cx, global, eval);
+}
+
+JS_FRIEND_API(void)
+js::SetReservedOrProxyPrivateSlotWithBarrier(JSObject* obj, size_t slot, const js::Value& value)
+{
+    if (IsProxy(obj)) {
+        MOZ_ASSERT(slot == 0);
+        obj->as<ProxyObject>().setSameCompartmentPrivate(value);
+    } else {
+        obj->as<NativeObject>().setSlot(slot, value);
+    }
+}
+
+void
+js::SetPreserveWrapperCallback(JSContext* cx, PreserveWrapperCallback callback)
+{
+    cx->preserveWrapperCallback = callback;
+}
+
+/*
+ * The below code is for temporary telemetry use. It can be removed when
+ * sufficient data has been harvested.
+ */
+
+namespace js {
+// Defined in vm/GlobalObject.cpp.
+extern size_t sSetProtoCalled;
+} // namespace js
+
+JS_FRIEND_API(size_t)
+JS_SetProtoCalled(JSContext*)
+{
+    return sSetProtoCalled;
+}
+
+// Defined in jsiter.cpp.
+extern size_t sCustomIteratorCount;
+
+JS_FRIEND_API(size_t)
+JS_GetCustomIteratorCount(JSContext* cx)
+{
+    return sCustomIteratorCount;
+}
+
+JS_FRIEND_API(unsigned)
+JS_PCToLineNumber(JSScript* script, jsbytecode* pc, unsigned* columnp)
+{
+    return PCToLineNumber(script, pc, columnp);
+}
+
+JS_FRIEND_API(bool)
+JS_IsDeadWrapper(JSObject* obj)
+{
+    return IsDeadProxyObject(obj);
+}
+
+void
+js::TraceWeakMaps(WeakMapTracer* trc)
+{
+    WeakMapBase::traceAllMappings(trc);
+    WatchpointMap::traceAll(trc);
+}
+
+extern JS_FRIEND_API(bool)
+js::AreGCGrayBitsValid(JSContext* cx)
+{
+    return cx->areGCGrayBitsValid();
+}
+
+JS_FRIEND_API(bool)
+js::ZoneGlobalsAreAllGray(JS::Zone* zone)
+{
+    for (CompartmentsInZoneIter comp(zone); !comp.done(); comp.next()) {
+        JSObject* obj = comp->unsafeUnbarrieredMaybeGlobal();
+        if (!obj || !JS::ObjectIsMarkedGray(obj))
+            return false;
+    }
+    return true;
+}
+
+namespace {
+struct VisitGrayCallbackFunctor {
+    GCThingCallback callback_;
+    void* closure_;
+    VisitGrayCallbackFunctor(GCThingCallback callback, void* closure)
+      : callback_(callback), closure_(closure)
+    {}
+
+    template <class T>
+    void operator()(T tp) const {
+        if ((*tp)->isTenured() && (*tp)->asTenured().isMarked(gc::GRAY))
+            callback_(closure_, JS::GCCellPtr(*tp));
+    }
+};
+} // namespace (anonymous)
+
+JS_FRIEND_API(void)
+js::VisitGrayWrapperTargets(Zone* zone, GCThingCallback callback, void* closure)
+{
+    for (CompartmentsInZoneIter comp(zone); !comp.done(); comp.next()) {
+        for (JSCompartment::WrapperEnum e(comp); !e.empty(); e.popFront())
+            e.front().mutableKey().applyToWrapped(VisitGrayCallbackFunctor(callback, closure));
+    }
+}
+
+JS_FRIEND_API(JSObject*)
+js::GetWeakmapKeyDelegate(JSObject* key)
+{
+    if (JSWeakmapKeyDelegateOp op = key->getClass()->extWeakmapKeyDelegateOp())
+        return op(key);
+    return nullptr;
+}
+
+JS_FRIEND_API(JSLinearString*)
+js::StringToLinearStringSlow(JSContext* cx, JSString* str)
+{
+    return str->ensureLinear(cx);
+}
+
+JS_FRIEND_API(void)
+JS_SetAccumulateTelemetryCallback(JSContext* cx, JSAccumulateTelemetryDataCallback callback)
+{
+    cx->setTelemetryCallback(cx, callback);
+}
+
+JS_FRIEND_API(JSObject*)
+JS_CloneObject(JSContext* cx, HandleObject obj, HandleObject protoArg)
+{
+    Rooted<TaggedProto> proto(cx, TaggedProto(protoArg.get()));
+    return CloneObject(cx, obj, proto);
+}
+
+#ifdef DEBUG
+
+JS_FRIEND_API(void)
+js::DumpString(JSString* str, FILE* fp)
+{
+    str->dump(fp);
+}
+
+JS_FRIEND_API(void)
+js::DumpAtom(JSAtom* atom, FILE* fp)
+{
+    atom->dump(fp);
+}
+
+JS_FRIEND_API(void)
+js::DumpChars(const char16_t* s, size_t n, FILE* fp)
+{
+    fprintf(fp, "char16_t * (%p) = ", (void*) s);
+    JSString::dumpChars(s, n, fp);
+    fputc('\n', fp);
+}
+
+JS_FRIEND_API(void)
+js::DumpObject(JSObject* obj, FILE* fp)
+{
+    if (!obj) {
+        fprintf(fp, "NULL\n");
+        return;
+    }
+    obj->dump(fp);
+}
+
+JS_FRIEND_API(void)
+js::DumpString(JSString* str) {
+    DumpString(str, stderr);
+}
+JS_FRIEND_API(void)
+js::DumpAtom(JSAtom* atom) {
+    DumpAtom(atom, stderr);
+}
+JS_FRIEND_API(void)
+js::DumpObject(JSObject* obj) {
+    DumpObject(obj, stderr);
+}
+JS_FRIEND_API(void)
+js::DumpChars(const char16_t* s, size_t n) {
+    DumpChars(s, n, stderr);
+}
+JS_FRIEND_API(void)
+js::DumpValue(const JS::Value& val) {
+    DumpValue(val, stderr);
+}
+JS_FRIEND_API(void)
+js::DumpId(jsid id) {
+    DumpId(id, stderr);
+}
+JS_FRIEND_API(void)
+js::DumpInterpreterFrame(JSContext* cx, InterpreterFrame* start)
+{
+    DumpInterpreterFrame(cx, stderr, start);
+}
+JS_FRIEND_API(bool)
+js::DumpPC(JSContext* cx) {
+    return DumpPC(cx, stdout);
+}
+JS_FRIEND_API(bool)
+js::DumpScript(JSContext* cx, JSScript* scriptArg)
+{
+    return DumpScript(cx, scriptArg, stdout);
+}
+
+#endif
+
+static const char*
+FormatValue(JSContext* cx, const Value& vArg, JSAutoByteString& bytes)
+{
+    RootedValue v(cx, vArg);
+
+    if (v.isMagic(JS_OPTIMIZED_OUT))
+        return "[unavailable]";
+
+    /*
+     * We could use Maybe<AutoCompartment> here, but G++ can't quite follow
+     * that, and warns about uninitialized members being used in the
+     * destructor.
+     */
+    RootedString str(cx);
+    if (v.isObject()) {
+        AutoCompartment ac(cx, &v.toObject());
+        str = ToString<CanGC>(cx, v);
+    } else {
+        str = ToString<CanGC>(cx, v);
+    }
+
+    if (!str)
+        return nullptr;
+    const char* buf = bytes.encodeLatin1(cx, str);
+    if (!buf)
+        return nullptr;
+    const char* found = strstr(buf, "function ");
+    if (found && (found - buf <= 2))
+        return "[function]";
+    return buf;
+}
+
+// Wrapper for JS_sprintf_append() that reports allocation failure to the
+// context.
+static char*
+MOZ_FORMAT_PRINTF(3, 4)
+sprintf_append(JSContext* cx, char* buf, const char* fmt, ...)
+{
+    va_list ap;
+
+    va_start(ap, fmt);
+    char* result = JS_vsprintf_append(buf, fmt, ap);
+    va_end(ap);
+
+    if (!result) {
+        ReportOutOfMemory(cx);
+        return nullptr;
+    }
+
+    return result;
+}
+
+static char*
+FormatFrame(JSContext* cx, const FrameIter& iter, char* buf, int num,
+            bool showArgs, bool showLocals, bool showThisProps)
+{
+    MOZ_ASSERT(!cx->isExceptionPending());
+    RootedScript script(cx, iter.script());
+    jsbytecode* pc = iter.pc();
+
+    RootedObject envChain(cx, iter.environmentChain(cx));
+    JSAutoCompartment ac(cx, envChain);
+
+    const char* filename = script->filename();
+    unsigned lineno = PCToLineNumber(script, pc);
+    RootedFunction fun(cx, iter.maybeCallee(cx));
+    RootedString funname(cx);
+    if (fun)
+        funname = fun->displayAtom();
+
+    RootedValue thisVal(cx);
+    if (iter.hasUsableAbstractFramePtr() &&
+        iter.isFunctionFrame() &&
+        fun && !fun->isArrow() && !fun->isDerivedClassConstructor() &&
+        !(fun->isBoundFunction() && iter.isConstructing()))
+    {
+        if (!GetFunctionThis(cx, iter.abstractFramePtr(), &thisVal))
+            return nullptr;
+    }
+
+    // print the frame number and function name
+    if (funname) {
+        JSAutoByteString funbytes;
+        char* str = funbytes.encodeLatin1(cx, funname);
+        if (!str)
+            return nullptr;
+        buf = sprintf_append(cx, buf, "%d %s(", num, str);
+    } else if (fun) {
+        buf = sprintf_append(cx, buf, "%d anonymous(", num);
+    } else {
+        buf = sprintf_append(cx, buf, "%d <TOP LEVEL>", num);
+    }
+    if (!buf)
+        return nullptr;
+
+    if (showArgs && iter.hasArgs()) {
+        PositionalFormalParameterIter fi(script);
+        bool first = true;
+        for (unsigned i = 0; i < iter.numActualArgs(); i++) {
+            RootedValue arg(cx);
+            if (i < iter.numFormalArgs() && fi.closedOver()) {
+                arg = iter.callObj(cx).aliasedBinding(fi);
+            } else if (iter.hasUsableAbstractFramePtr()) {
+                if (script->analyzedArgsUsage() &&
+                    script->argsObjAliasesFormals() &&
+                    iter.hasArgsObj())
+                {
+                    arg = iter.argsObj().arg(i);
+                } else {
+                    arg = iter.unaliasedActual(i, DONT_CHECK_ALIASING);
+                }
+            } else {
+                arg = MagicValue(JS_OPTIMIZED_OUT);
+            }
+
+            JSAutoByteString valueBytes;
+            const char* value = FormatValue(cx, arg, valueBytes);
+            if (!value) {
+                if (cx->isThrowingOutOfMemory())
+                    return nullptr;
+                cx->clearPendingException();
+            }
+
+            JSAutoByteString nameBytes;
+            const char* name = nullptr;
+
+            if (i < iter.numFormalArgs()) {
+                MOZ_ASSERT(fi.argumentSlot() == i);
+                if (!fi.isDestructured()) {
+                    name = nameBytes.encodeLatin1(cx, fi.name());
+                    if (!name)
+                        return nullptr;
+                } else {
+                    name = "(destructured parameter)";
+                }
+                fi++;
+            }
+
+            if (value) {
+                buf = sprintf_append(cx, buf, "%s%s%s%s%s%s",
+                                     !first ? ", " : "",
+                                     name ? name :"",
+                                     name ? " = " : "",
+                                     arg.isString() ? "\"" : "",
+                                     value,
+                                     arg.isString() ? "\"" : "");
+                if (!buf)
+                    return nullptr;
+
+                first = false;
+            } else {
+                buf = sprintf_append(cx, buf,
+                                     "    <Failed to get argument while inspecting stack frame>\n");
+                if (!buf)
+                    return nullptr;
+
+            }
+        }
+    }
+
+    // print filename and line number
+    buf = sprintf_append(cx, buf, "%s [\"%s\":%d]\n",
+                         fun ? ")" : "",
+                         filename ? filename : "<unknown>",
+                         lineno);
+    if (!buf)
+        return nullptr;
+
+
+    // Note: Right now we don't dump the local variables anymore, because
+    // that is hard to support across all the JITs etc.
+
+    // print the value of 'this'
+    if (showLocals) {
+        if (!thisVal.isUndefined()) {
+            JSAutoByteString thisValBytes;
+            RootedString thisValStr(cx, ToString<CanGC>(cx, thisVal));
+            if (!thisValStr) {
+                if (cx->isThrowingOutOfMemory())
+                    return nullptr;
+                cx->clearPendingException();
+            }
+            if (thisValStr) {
+                const char* str = thisValBytes.encodeLatin1(cx, thisValStr);
+                if (!str)
+                    return nullptr;
+                buf = sprintf_append(cx, buf, "    this = %s\n", str);
+            } else {
+                buf = sprintf_append(cx, buf, "    <failed to get 'this' value>\n");
+            }
+            if (!buf)
+                return nullptr;
+        }
+    }
+
+    if (showThisProps && thisVal.isObject()) {
+        RootedObject obj(cx, &thisVal.toObject());
+
+        AutoIdVector keys(cx);
+        if (!GetPropertyKeys(cx, obj, JSITER_OWNONLY, &keys)) {
+            if (cx->isThrowingOutOfMemory())
+                return nullptr;
+            cx->clearPendingException();
+        }
+
+        RootedId id(cx);
+        for (size_t i = 0; i < keys.length(); i++) {
+            RootedId id(cx, keys[i]);
+            RootedValue key(cx, IdToValue(id));
+            RootedValue v(cx);
+
+            if (!GetProperty(cx, obj, obj, id, &v)) {
+                if (cx->isThrowingOutOfMemory())
+                    return nullptr;
+                cx->clearPendingException();
+                buf = sprintf_append(cx, buf,
+                                     "    <Failed to fetch property while inspecting stack frame>\n");
+                if (!buf)
+                    return nullptr;
+                continue;
+            }
+
+            JSAutoByteString nameBytes;
+            const char* name = FormatValue(cx, key, nameBytes);
+            if (!name) {
+                if (cx->isThrowingOutOfMemory())
+                    return nullptr;
+                cx->clearPendingException();
+            }
+
+            JSAutoByteString valueBytes;
+            const char* value = FormatValue(cx, v, valueBytes);
+            if (!value) {
+                if (cx->isThrowingOutOfMemory())
+                    return nullptr;
+                cx->clearPendingException();
+            }
+
+            if (name && value) {
+                buf = sprintf_append(cx, buf, "    this.%s = %s%s%s\n",
+                                     name,
+                                     v.isString() ? "\"" : "",
+                                     value,
+                                     v.isString() ? "\"" : "");
+            } else {
+                buf = sprintf_append(cx, buf,
+                                     "    <Failed to format values while inspecting stack frame>\n");
+            }
+            if (!buf)
+                return nullptr;
+        }
+    }
+
+    MOZ_ASSERT(!cx->isExceptionPending());
+    return buf;
+}
+
+static char*
+FormatWasmFrame(JSContext* cx, const FrameIter& iter, char* buf, int num, bool showArgs)
+{
+    JSAtom* functionDisplayAtom = iter.functionDisplayAtom();
+    UniqueChars nameStr;
+    if (functionDisplayAtom)
+        nameStr = StringToNewUTF8CharsZ(cx, *functionDisplayAtom);
+
+    buf = sprintf_append(cx, buf, "%d %s()",
+                         num,
+                         nameStr ? nameStr.get() : "<wasm-function>");
+    if (!buf)
+        return nullptr;
+    const char* filename = iter.filename();
+    uint32_t lineno = iter.computeLine();
+    buf = sprintf_append(cx, buf, " [\"%s\":%d]\n",
+                         filename ? filename : "<unknown>",
+                         lineno);
+
+    MOZ_ASSERT(!cx->isExceptionPending());
+    return buf;
+}
+
+JS_FRIEND_API(char*)
+JS::FormatStackDump(JSContext* cx, char* buf, bool showArgs, bool showLocals, bool showThisProps)
+{
+    int num = 0;
+
+    for (AllFramesIter i(cx); !i.done(); ++i) {
+        if (i.hasScript())
+            buf = FormatFrame(cx, i, buf, num, showArgs, showLocals, showThisProps);
+        else
+            buf = FormatWasmFrame(cx, i, buf, num, showArgs);
+        if (!buf)
+            return nullptr;
+        num++;
+    }
+
+    if (!num)
+        buf = JS_sprintf_append(buf, "JavaScript stack is empty\n");
+
+    return buf;
+}
+
+extern JS_FRIEND_API(bool)
+JS::ForceLexicalInitialization(JSContext *cx, HandleObject obj)
+{
+    AssertHeapIsIdle(cx);
+    CHECK_REQUEST(cx);
+    assertSameCompartment(cx, obj);
+
+    bool initializedAny = false;
+    NativeObject* nobj = &obj->as<NativeObject>();
+
+    for (Shape::Range<NoGC> r(nobj->lastProperty()); !r.empty(); r.popFront()) {
+        Shape* s = &r.front();
+        Value v = nobj->getSlot(s->slot());
+        if (s->hasSlot() && v.isMagic() && v.whyMagic() == JS_UNINITIALIZED_LEXICAL) {
+            nobj->setSlot(s->slot(), UndefinedValue());
+            initializedAny = true;
+        }
+
+    }
+    return initializedAny;
+}
+
+struct DumpHeapTracer : public JS::CallbackTracer, public WeakMapTracer
+{
+    const char* prefix;
+    FILE* output;
+
+    DumpHeapTracer(FILE* fp, JSContext* cx)
+      : JS::CallbackTracer(cx, DoNotTraceWeakMaps),
+        js::WeakMapTracer(cx), prefix(""), output(fp)
+    {}
+
+  private:
+    void trace(JSObject* map, JS::GCCellPtr key, JS::GCCellPtr value) override {
+        JSObject* kdelegate = nullptr;
+        if (key.is<JSObject>())
+            kdelegate = js::GetWeakmapKeyDelegate(&key.as<JSObject>());
+
+        fprintf(output, "WeakMapEntry map=%p key=%p keyDelegate=%p value=%p\n",
+                map, key.asCell(), kdelegate, value.asCell());
+    }
+
+    void onChild(const JS::GCCellPtr& thing) override;
+};
+
+static char
+MarkDescriptor(void* thing)
+{
+    gc::TenuredCell* cell = gc::TenuredCell::fromPointer(thing);
+    if (cell->isMarked(gc::BLACK))
+        return cell->isMarked(gc::GRAY) ? 'G' : 'B';
+    else
+        return cell->isMarked(gc::GRAY) ? 'X' : 'W';
+}
+
+static void
+DumpHeapVisitZone(JSRuntime* rt, void* data, Zone* zone)
+{
+    DumpHeapTracer* dtrc = static_cast<DumpHeapTracer*>(data);
+    fprintf(dtrc->output, "# zone %p\n", (void*)zone);
+}
+
+static void
+DumpHeapVisitCompartment(JSContext* cx, void* data, JSCompartment* comp)
+{
+    char name[1024];
+    if (cx->compartmentNameCallback)
+        (*cx->compartmentNameCallback)(cx, comp, name, sizeof(name));
+    else
+        strcpy(name, "<unknown>");
+
+    DumpHeapTracer* dtrc = static_cast<DumpHeapTracer*>(data);
+    fprintf(dtrc->output, "# compartment %s [in zone %p]\n", name, (void*)comp->zone());
+}
+
+static void
+DumpHeapVisitArena(JSRuntime* rt, void* data, gc::Arena* arena,
+                   JS::TraceKind traceKind, size_t thingSize)
+{
+    DumpHeapTracer* dtrc = static_cast<DumpHeapTracer*>(data);
+    fprintf(dtrc->output, "# arena allockind=%u size=%u\n",
+            unsigned(arena->getAllocKind()), unsigned(thingSize));
+}
+
+static void
+DumpHeapVisitCell(JSRuntime* rt, void* data, void* thing,
+                  JS::TraceKind traceKind, size_t thingSize)
+{
+    DumpHeapTracer* dtrc = static_cast<DumpHeapTracer*>(data);
+    char cellDesc[1024 * 32];
+    JS_GetTraceThingInfo(cellDesc, sizeof(cellDesc), dtrc, thing, traceKind, true);
+    fprintf(dtrc->output, "%p %c %s\n", thing, MarkDescriptor(thing), cellDesc);
+    js::TraceChildren(dtrc, thing, traceKind);
+}
+
+void
+DumpHeapTracer::onChild(const JS::GCCellPtr& thing)
+{
+    if (gc::IsInsideNursery(thing.asCell()))
+        return;
+
+    char buffer[1024];
+    getTracingEdgeName(buffer, sizeof(buffer));
+    fprintf(output, "%s%p %c %s\n", prefix, thing.asCell(), MarkDescriptor(thing.asCell()), buffer);
+}
+
+void
+js::DumpHeap(JSContext* cx, FILE* fp, js::DumpHeapNurseryBehaviour nurseryBehaviour)
+{
+    if (nurseryBehaviour == js::CollectNurseryBeforeDump)
+        cx->gc.evictNursery(JS::gcreason::API);
+
+    DumpHeapTracer dtrc(fp, cx);
+    fprintf(dtrc.output, "# Roots.\n");
+    TraceRuntime(&dtrc);
+
+    fprintf(dtrc.output, "# Weak maps.\n");
+    WeakMapBase::traceAllMappings(&dtrc);
+
+    fprintf(dtrc.output, "==========\n");
+
+    dtrc.prefix = "> ";
+    IterateZonesCompartmentsArenasCells(cx, &dtrc,
+                                        DumpHeapVisitZone,
+                                        DumpHeapVisitCompartment,
+                                        DumpHeapVisitArena,
+                                        DumpHeapVisitCell);
+
+    fflush(dtrc.output);
+}
+
+JS_FRIEND_API(void)
+js::SetActivityCallback(JSContext* cx, ActivityCallback cb, void* arg)
+{
+    cx->activityCallback = cb;
+    cx->activityCallbackArg = arg;
+}
+
+JS_FRIEND_API(void)
+JS::NotifyDidPaint(JSContext* cx)
+{
+    cx->gc.notifyDidPaint();
+}
+
+JS_FRIEND_API(void)
+JS::PokeGC(JSContext* cx)
+{
+    cx->gc.poke();
+}
+
+JS_FRIEND_API(JSCompartment*)
+js::GetAnyCompartmentInZone(JS::Zone* zone)
+{
+    CompartmentsInZoneIter comp(zone);
+    MOZ_ASSERT(!comp.done());
+    return comp.get();
+}
+
+void
+JS::ObjectPtr::finalize(JSRuntime* rt)
+{
+    if (IsIncrementalBarrierNeeded(rt->contextFromMainThread()))
+        IncrementalObjectBarrier(value);
+    value = nullptr;
+}
+
+void
+JS::ObjectPtr::finalize(JSContext* cx)
+{
+    finalize(cx->runtime());
+}
+
+void
+JS::ObjectPtr::updateWeakPointerAfterGC()
+{
+    if (js::gc::IsAboutToBeFinalizedUnbarriered(value.unsafeGet()))
+        value = nullptr;
+}
+
+void
+JS::ObjectPtr::trace(JSTracer* trc, const char* name)
+{
+    JS::TraceEdge(trc, &value, name);
+}
+
+JS_FRIEND_API(JSObject*)
+js::GetTestingFunctions(JSContext* cx)
+{
+    RootedObject obj(cx, JS_NewPlainObject(cx));
+    if (!obj)
+        return nullptr;
+
+    if (!DefineTestingFunctions(cx, obj, false, false))
+        return nullptr;
+
+    return obj;
+}
+
+#ifdef DEBUG
+JS_FRIEND_API(unsigned)
+js::GetEnterCompartmentDepth(JSContext* cx)
+{
+  return cx->getEnterCompartmentDepth();
+}
+#endif
+
+JS_FRIEND_API(void)
+js::SetDOMCallbacks(JSContext* cx, const DOMCallbacks* callbacks)
+{
+    cx->DOMcallbacks = callbacks;
+}
+
+JS_FRIEND_API(const DOMCallbacks*)
+js::GetDOMCallbacks(JSContext* cx)
+{
+    return cx->DOMcallbacks;
+}
+
+static const void* gDOMProxyHandlerFamily = nullptr;
+static uint32_t gDOMProxyExpandoSlot = 0;
+static DOMProxyShadowsCheck gDOMProxyShadowsCheck;
+
+JS_FRIEND_API(void)
+js::SetDOMProxyInformation(const void* domProxyHandlerFamily, uint32_t domProxyExpandoSlot,
+                           DOMProxyShadowsCheck domProxyShadowsCheck)
+{
+    gDOMProxyHandlerFamily = domProxyHandlerFamily;
+    gDOMProxyExpandoSlot = domProxyExpandoSlot;
+    gDOMProxyShadowsCheck = domProxyShadowsCheck;
+}
+
+const void*
+js::GetDOMProxyHandlerFamily()
+{
+    return gDOMProxyHandlerFamily;
+}
+
+uint32_t
+js::GetDOMProxyExpandoSlot()
+{
+    return gDOMProxyExpandoSlot;
+}
+
+DOMProxyShadowsCheck
+js::GetDOMProxyShadowsCheck()
+{
+    return gDOMProxyShadowsCheck;
+}
+
+bool
+js::detail::IdMatchesAtom(jsid id, JSAtom* atom)
+{
+    return id == INTERNED_STRING_TO_JSID(nullptr, atom);
+}
+
+JS_FRIEND_API(void)
+js::PrepareScriptEnvironmentAndInvoke(JSContext* cx, HandleObject scope, ScriptEnvironmentPreparer::Closure& closure)
+{
+    MOZ_ASSERT(!cx->isExceptionPending());
+
+    MOZ_RELEASE_ASSERT(cx->runtime()->scriptEnvironmentPreparer,
+                       "Embedding needs to set a scriptEnvironmentPreparer callback");
+
+    cx->runtime()->scriptEnvironmentPreparer->invoke(scope, closure);
+}
+
+JS_FRIEND_API(void)
+js::SetScriptEnvironmentPreparer(JSContext* cx, ScriptEnvironmentPreparer* preparer)
+{
+    cx->scriptEnvironmentPreparer = preparer;
+}
+
+JS_FRIEND_API(void)
+js::SetCTypesActivityCallback(JSContext* cx, CTypesActivityCallback cb)
+{
+    cx->ctypesActivityCallback = cb;
+}
+
+js::AutoCTypesActivityCallback::AutoCTypesActivityCallback(JSContext* cx,
+                                                           js::CTypesActivityType beginType,
+                                                           js::CTypesActivityType endType
+                                                           MOZ_GUARD_OBJECT_NOTIFIER_PARAM_IN_IMPL)
+  : cx(cx), callback(cx->runtime()->ctypesActivityCallback), endType(endType)
+{
+    MOZ_GUARD_OBJECT_NOTIFIER_INIT;
+
+    if (callback)
+        callback(cx, beginType);
+}
+
+JS_FRIEND_API(void)
+js::SetAllocationMetadataBuilder(JSContext* cx, const AllocationMetadataBuilder *callback)
+{
+    cx->compartment()->setAllocationMetadataBuilder(callback);
+}
+
+JS_FRIEND_API(JSObject*)
+js::GetAllocationMetadata(JSObject* obj)
+{
+    ObjectWeakMap* map = obj->compartment()->objectMetadataTable;
+    if (map)
+        return map->lookup(obj);
+    return nullptr;
+}
+
+JS_FRIEND_API(bool)
+js::ReportIsNotFunction(JSContext* cx, HandleValue v)
+{
+    return ReportIsNotFunction(cx, v, -1);
+}
+
+JS_FRIEND_API(void)
+js::ReportASCIIErrorWithId(JSContext* cx, const char* msg, HandleId id)
+{
+    RootedValue idv(cx);
+    if (!JS_IdToValue(cx, id, &idv))
+        return;
+    RootedString idstr(cx, JS::ToString(cx, idv));
+    if (!idstr)
+        return;
+    JSAutoByteString bytes;
+    if (!bytes.encodeUtf8(cx, idstr))
+        return;
+    JS_ReportErrorUTF8(cx, msg, bytes.ptr());
+}
+
+#ifdef DEBUG
+bool
+js::HasObjectMovedOp(JSObject* obj) {
+    return !!GetObjectClass(obj)->extObjectMovedOp();
+}
+#endif
+
+JS_FRIEND_API(bool)
+js::ForwardToNative(JSContext* cx, JSNative native, const CallArgs& args)
+{
+    return native(cx, args.length(), args.base());
+}
+
+JS_FRIEND_API(JSObject*)
+js::ConvertArgsToArray(JSContext* cx, const CallArgs& args)
+{
+    RootedObject argsArray(cx, NewDenseCopiedArray(cx, args.length(), args.array()));
+    return argsArray;
+}
+
+JS_FRIEND_API(JSAtom*)
+js::GetPropertyNameFromPC(JSScript* script, jsbytecode* pc)
+{
+    if (!IsGetPropPC(pc) && !IsSetPropPC(pc))
+        return nullptr;
+    return script->getName(pc);
+}
+
+JS_FRIEND_API(void)
+js::SetWindowProxyClass(JSContext* cx, const js::Class* clasp)
+{
+    MOZ_ASSERT(!cx->maybeWindowProxyClass());
+    cx->setWindowProxyClass(clasp);
+}
+
+JS_FRIEND_API(void)
+js::SetWindowProxy(JSContext* cx, HandleObject global, HandleObject windowProxy)
+{
+    AssertHeapIsIdle(cx);
+    CHECK_REQUEST(cx);
+
+    assertSameCompartment(cx, global, windowProxy);
+
+    MOZ_ASSERT(IsWindowProxy(windowProxy));
+    global->as<GlobalObject>().setWindowProxy(windowProxy);
+}
+
+JS_FRIEND_API(JSObject*)
+js::ToWindowIfWindowProxy(JSObject* obj)
+{
+    if (IsWindowProxy(obj))
+        return &obj->global();
+    return obj;
+}
+
+JS_FRIEND_API(JSObject*)
+js::ToWindowProxyIfWindow(JSObject* obj)
+{
+    if (IsWindow(obj))
+        return obj->as<GlobalObject>().windowProxy();
+    return obj;
+}
+
+JS_FRIEND_API(bool)
+js::IsWindowProxy(JSObject* obj)
+{
+    // Note: simply checking `obj == obj->global().windowProxy()` is not
+    // sufficient: we may have transplanted the window proxy with a CCW.
+    // Check the Class to ensure we really have a window proxy.
+    return obj->getClass() == obj->runtimeFromAnyThread()->maybeWindowProxyClass();
+}
+
+JS_FRIEND_API(bool)
+js::detail::IsWindowSlow(JSObject* obj)
+{
+    return obj->as<GlobalObject>().maybeWindowProxy();
+}