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

modules/push_messaging/PushSubscription.idl

 // Copyright 2014 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://w3c.github.io/push-api/#pushsubscription-interface
 
+enum PushEncryptionKeyName {
+    "p256dh",
+    "auth"
+};
+
 [
     Exposed=(Window,ServiceWorker),
     GarbageCollected,
     RuntimeEnabled=PushMessaging,
 ] interface PushSubscription {
     readonly attribute USVString endpoint;
+
+    [RuntimeEnabled=PushMessagingData] ArrayBuffer? getKey(PushEncryptionKeyName name);
     [CallWith=ScriptState] Promise<boolean> unsubscribe();
 
-    serializer = { attribute };
+    serializer;
 };