diff -r 000000000000 -r 6474c204b198 js/src/vm/WrapperObject.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/vm/WrapperObject.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,45 @@
+/* -*- 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_WrapperObject_h
+#define vm_WrapperObject_h
+
+#include "jsobj.h"
+#include "jswrapper.h"
+
+#include "vm/ProxyObject.h"
+
+namespace js {
+
+// Proxy family for wrappers.
+// This variable exists solely to provide a unique address for use as an identifier.
+extern const char sWrapperFamily;
+
+class WrapperObject : public ProxyObject
+{
+};
+
+class CrossCompartmentWrapperObject : public WrapperObject
+{
+};
+
+} // namespace js
+
+template<>
+inline bool
+JSObject::is<js::WrapperObject>() const
+{
+    return IsWrapper(const_cast<JSObject*>(this));
+}
+
+template<>
+inline bool
+JSObject::is<js::CrossCompartmentWrapperObject>() const
+{
+    return IsCrossCompartmentWrapper(const_cast<JSObject*>(this));
+}
+
+#endif /* vm_WrapperObject_h */