diff -r 000000000000 -r 6474c204b198 js/xpconnect/src/qsObjectHelper.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/xpconnect/src/qsObjectHelper.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,54 @@
+/* -*- 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/. */
+
+#ifndef qsObjectHelper_h
+#define qsObjectHelper_h
+
+#include "xpcObjectHelper.h"
+
+#include "nsAutoPtr.h"
+#include "nsCOMPtr.h"
+#include "nsWrapperCache.h"
+#include "mozilla/TypeTraits.h"
+
+class qsObjectHelper : public xpcObjectHelper
+{
+public:
+    template <class T>
+    inline
+    qsObjectHelper(T *aObject, nsWrapperCache *aCache)
+        : xpcObjectHelper(ToSupports(aObject), ToCanonicalSupports(aObject),
+                          aCache)
+    {}
+
+    template <class T>
+    inline
+    qsObjectHelper(nsCOMPtr<T>& aObject, nsWrapperCache *aCache)
+        : xpcObjectHelper(ToSupports(aObject.get()),
+                          ToCanonicalSupports(aObject.get()), aCache)
+    {
+        if (mCanonical) {
+            // Transfer the strong reference.
+            mCanonicalStrong = dont_AddRef(mCanonical);
+            aObject.forget();
+        }
+    }
+
+    template <class T>
+    inline
+    qsObjectHelper(nsRefPtr<T>& aObject, nsWrapperCache *aCache)
+        : xpcObjectHelper(ToSupports(aObject.get()),
+                          ToCanonicalSupports(aObject.get()), aCache)
+    {
+        if (mCanonical) {
+            // Transfer the strong reference.
+            mCanonicalStrong = dont_AddRef(mCanonical);
+            aObject.forget();
+        }
+    }
+};
+
+#endif