diff -r 000000000000 -r 6474c204b198 content/base/src/nsStubMutationObserver.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/content/base/src/nsStubMutationObserver.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,16 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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/. */
+
+/*
+ * nsStubMutationObserver is an implementation of the nsIMutationObserver
+ * interface (except for the methods on nsISupports) that is intended to be
+ * used as a base class within the content/layout library.  All methods do
+ * nothing.
+ */
+
+#include "nsStubMutationObserver.h"
+
+NS_IMPL_NSIMUTATIONOBSERVER_CORE_STUB(nsStubMutationObserver)
+NS_IMPL_NSIMUTATIONOBSERVER_CONTENT(nsStubMutationObserver)