diff -r 000000000000 -r 6474c204b198 dom/base/nsIGlobalObject.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/base/nsIGlobalObject.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,18 @@
+/* -*- Mode: C++; tab-width: 2; 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/. */
+
+#include "nsIGlobalObject.h"
+#include "nsContentUtils.h"
+
+nsIPrincipal*
+nsIGlobalObject::PrincipalOrNull()
+{
+  JSObject *global = GetGlobalJSObject();
+  if (NS_WARN_IF(!global))
+    return nullptr;
+
+  return nsContentUtils::GetObjectPrincipal(global);
+}