diff -r 000000000000 -r 6474c204b198 dom/webidl/MediaStreamEvent.webidl
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/webidl/MediaStreamEvent.webidl	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,18 @@
+/* -*- Mode: IDL; 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/.
+ *
+ * The origin of this IDL file is
+ * http://dev.w3.org/2011/webrtc/editor/webrtc.html#mediastreamevent
+ */
+
+dictionary MediaStreamEventInit : EventInit {
+    MediaStream? stream = null;
+};
+
+[Pref="media.peerconnection.enabled",
+ Constructor(DOMString type, optional MediaStreamEventInit eventInitDict)]
+interface MediaStreamEvent : Event {
+  readonly attribute MediaStream? stream;
+};