ServiceWorker: Remove [Unforgeable] idl extended attribute.

third_party/WebKit/Source/modules/serviceworkers/ServiceWorkerContainer.idl

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 13 matching lines @@
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 // https://slightlyoff.github.io/ServiceWorker/spec/service_worker/index.html#service-worker-container-interface
 [
 ] interface ServiceWorkerContainer : EventTarget {
-    [Unforgeable] readonly attribute ServiceWorker? controller;
+    readonly attribute ServiceWorker? controller;
     [CallWith=ScriptState] readonly attribute Promise<ServiceWorkerRegistration> ready;
 
     [CallWith=ScriptState, ImplementedAs=registerServiceWorker] Promise<ServiceWorkerRegistration> register(USVString url, optional RegistrationOptions options);
     [CallWith=ScriptState] Promise<ServiceWorkerRegistration> getRegistration(optional USVString documentURL = "");
     [CallWith=ScriptState] Promise<sequence<ServiceWorkerRegistration>> getRegistrations();
 
     attribute EventHandler oncontrollerchange;
     attribute EventHandler onmessage;
 };