Roll 50: Copied IDLs, PYTHON scripts from WebKit removed deleted files in WebCore

modules/serviceworkers/ExtendableMessageEvent.idl

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// https://slightlyoff.github.io/ServiceWorker/spec/service_worker/index.html#extendablemessage-event-section
+
+[
+    // TODO(bashi): Stop using CustomConstructor once we solve reference
+    // circulation between Blink and V8. http://crbug.com/501866
+    // Constructor should be:
+    // Constructor(DOMString type, optional ExtendableMessageEventInit eventInitDict),
+    CustomConstructor,
+    Exposed=ServiceWorker,
+    RuntimeEnabled=ServiceWorkerExtendableMessageEvent,
+] interface ExtendableMessageEvent : ExtendableEvent {
+    [Custom=Getter] readonly attribute any data;
+    readonly attribute DOMString origin;
+    readonly attribute DOMString lastEventId;
+    [SameObject] readonly attribute (Client or ServiceWorker or MessagePort)? source;
+    [SameObject] readonly attribute MessagePort[]? ports;
+};