diff -r 000000000000 -r 6474c204b198 content/base/public/nsIContentInlines.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/content/base/public/nsIContentInlines.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,19 @@
+/* -*- Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil; tab-width: 8; -*- */
+/* vim: set sw=2 sts=2 ts=8 et 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/. */
+
+#ifndef nsIContentInlines_h
+#define nsIContentInlines_h
+
+#include "nsIContent.h"
+#include "nsIDocument.h"
+
+inline bool
+nsIContent::IsInHTMLDocument() const
+{
+  return OwnerDoc()->IsHTML();
+}
+
+#endif // nsIContentInlines_h