diff -r 000000000000 -r 6474c204b198 layout/xul/nsIContainerBoxObject.idl
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/layout/xul/nsIContainerBoxObject.idl	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,20 @@
+/* -*- 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/. */
+
+#include "nsISupports.idl"
+
+interface nsIDocShell;
+interface nsIBoxObject;
+
+[scriptable, uuid(35d4c04b-3bd3-4375-92e2-a818b4b4acb6)]
+interface nsIContainerBoxObject : nsISupports
+{
+  readonly attribute nsIDocShell docShell;
+};
+
+%{C++
+nsresult
+NS_NewContainerBoxObject(nsIBoxObject** aResult);
+%}