diff -r 000000000000 -r 6474c204b198 xpcom/glue/HoldDropJSObjects.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/glue/HoldDropJSObjects.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,71 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_HoldDropJSObjects_h
+#define mozilla_HoldDropJSObjects_h
+
+#include "mozilla/TypeTraits.h"
+#include "nsCycleCollectionParticipant.h"
+
+class nsISupports;
+class nsScriptObjectTracer;
+
+// Only HoldJSObjects and DropJSObjects should be called directly.
+
+namespace mozilla {
+namespace cyclecollector {
+
+// These methods are defined in nsCycleCollector.cpp
+void HoldJSObjectsImpl(void* aHolder, nsScriptObjectTracer* aTracer);
+void HoldJSObjectsImpl(nsISupports* aHolder);
+void DropJSObjectsImpl(void* aHolder);
+void DropJSObjectsImpl(nsISupports* aHolder);
+
+} // namespace cyclecollector
+
+
+template<class T, bool isISupports=IsBaseOf<nsISupports, T>::value>
+struct HoldDropJSObjectsHelper
+{
+  static void Hold(T* aHolder)
+  {
+    cyclecollector::HoldJSObjectsImpl(aHolder, NS_CYCLE_COLLECTION_PARTICIPANT(T));
+  }
+  static void Drop(T* aHolder)
+  {
+    cyclecollector::DropJSObjectsImpl(aHolder);
+  }
+};
+
+template<class T>
+struct HoldDropJSObjectsHelper<T, true>
+{
+  static void Hold(T* aHolder)
+  {
+    cyclecollector::HoldJSObjectsImpl(ToSupports(aHolder));
+  }
+  static void Drop(T* aHolder)
+  {
+    cyclecollector::DropJSObjectsImpl(ToSupports(aHolder));
+  }
+};
+
+
+template<class T>
+void HoldJSObjects(T* aHolder)
+{
+  HoldDropJSObjectsHelper<T>::Hold(aHolder);
+}
+
+template<class T>
+void DropJSObjects(T* aHolder)
+{
+  HoldDropJSObjectsHelper<T>::Drop(aHolder);
+}
+
+} // namespace mozilla
+
+#endif // mozilla_HoldDropJSObjects_h