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

modules/serviceworkers/WindowClient.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://slightlyoff.github.io/ServiceWorker/spec/service_worker/#context-frame-type-enum
 enum ContextFrameType {
     "top-level",
     "nested",
     "auxiliary",
     "none"
 };
 
 // https://slightlyoff.github.io/ServiceWorker/spec/service_worker/#window-client-interface
 [
     Exposed=ServiceWorker,
     RuntimeEnabled=ServiceWorkerClientAttributes,
     GarbageCollected,
-    TypeChecking=Interface,
     ImplementedAs=ServiceWorkerWindowClient,
 ] interface WindowClient : Client {
     readonly attribute VisibilityState visibilityState;
     readonly attribute boolean focused;
     [CallWith=ScriptState] Promise<WindowClient> focus();
+    [RuntimeEnabled=ServiceWorkerWindowClientNavigate, CallWith=ScriptState] Promise<WindowClient> navigate(USVString url);
 };