diff -r 000000000000 -r 6474c204b198 dom/interfaces/events/nsIDOMMessageEvent.idl
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/interfaces/events/nsIDOMMessageEvent.idl	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,55 @@
+/* -*- 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/. */
+
+#include "nsIDOMEvent.idl"
+
+/**
+ * The nsIDOMMessageEvent interface is used for server-sent events and for
+ * cross-domain messaging.
+ *
+ * For more information on this interface, please see
+ * http://www.whatwg.org/specs/web-apps/current-work/#messageevent
+ */
+[scriptable, builtinclass, uuid(bb869a03-5fc0-4a1b-838a-342e5025fc05)]
+interface nsIDOMMessageEvent : nsIDOMEvent
+{
+  /**
+   * Custom string data associated with this event.
+   */
+  [implicit_jscontext]
+  readonly attribute jsval data;
+  
+  /**
+   * The origin of the site from which this event originated, which is the
+   * scheme, ":", and if the URI has a host, "//" followed by the
+   * host, and if the port is not the default for the given scheme,
+   * ":" followed by that port.  This value does not have a trailing slash.
+   */
+  readonly attribute DOMString origin;
+
+  /**
+   * The last event ID string of the event source, for server-sent DOM events; this
+   * value is the empty string for cross-origin messaging.
+   */
+  readonly attribute DOMString lastEventId;
+  
+  /**
+   * The window which originated this event.
+   */
+  readonly attribute nsIDOMWindow source;
+
+  /**
+   * Initializes this event with the given data, in a manner analogous to
+   * the similarly-named method on the nsIDOMEvent interface, also setting the
+   * data, origin, source, and lastEventId attributes of this appropriately.
+   */
+  void initMessageEvent(in DOMString aType,
+                        in boolean aCanBubble,
+                        in boolean aCancelable,
+                        in jsval aData,
+                        in DOMString aOrigin,
+                        in DOMString aLastEventId,
+                        in nsIDOMWindow aSource);
+};