diff -r 000000000000 -r 6474c204b198 dom/base/nsWrapperCacheInlines.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/base/nsWrapperCacheInlines.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,61 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsWrapperCacheInline_h___
+#define nsWrapperCacheInline_h___
+
+#include "nsWrapperCache.h"
+#include "js/GCAPI.h"
+#include "js/TracingAPI.h"
+
+inline JSObject*
+nsWrapperCache::GetWrapper() const
+{
+    JSObject* obj = GetWrapperPreserveColor();
+    if (obj) {
+      JS::ExposeObjectToActiveJS(obj);
+    }
+    return obj;
+}
+
+inline bool
+nsWrapperCache::IsBlack()
+{
+  JSObject* o = GetWrapperPreserveColor();
+  return o && !JS::GCThingIsMarkedGray(o);
+}
+
+static void
+SearchGray(void* aGCThing, const char* aName, void* aClosure)
+{
+  bool* hasGrayObjects = static_cast<bool*>(aClosure);
+  if (!*hasGrayObjects && aGCThing && JS::GCThingIsMarkedGray(aGCThing)) {
+    *hasGrayObjects = true;
+  }
+}
+
+inline bool
+nsWrapperCache::HasNothingToTrace(nsISupports* aThis)
+{
+  nsXPCOMCycleCollectionParticipant* participant = nullptr;
+  CallQueryInterface(aThis, &participant);
+  bool hasGrayObjects = false;
+  participant->Trace(aThis, TraceCallbackFunc(SearchGray), &hasGrayObjects);
+  return !hasGrayObjects;
+}
+
+inline bool
+nsWrapperCache::IsBlackAndDoesNotNeedTracing(nsISupports* aThis)
+{
+  return IsBlack() && HasNothingToTrace(aThis);
+}
+
+inline void
+nsWrapperCache::TraceWrapperJSObject(JSTracer* aTrc, const char* aName)
+{
+  JS_CallHeapObjectTracer(aTrc, &mWrapper, aName);
+}
+
+#endif /* nsWrapperCache_h___ */