diff -r 000000000000 -r 6474c204b198 js/src/vm/WeakMapObject.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/vm/WeakMapObject.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,27 @@
+/* -*- 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 vm_WeakMapObject_h
+#define vm_WeakMapObject_h
+
+#include "jsobj.h"
+#include "jsweakmap.h"
+
+namespace js {
+
+typedef WeakMap<EncapsulatedPtrObject, RelocatableValue> ObjectValueMap;
+
+class WeakMapObject : public JSObject
+{
+  public:
+    static const Class class_;
+
+    ObjectValueMap *getMap() { return static_cast<ObjectValueMap*>(getPrivate()); }
+};
+
+} // namespace js
+
+#endif /* vm_WeakMapObject_h */