Expose Fetch API related classes to Window and WorkerGlobalScope.

Source/modules/serviceworkers/Request.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.
 
 // http://fetch.spec.whatwg.org/#request-class
 
 typedef (Request or USVString) RequestInfo;
 
 enum RequestMode { "same-origin", "no-cors", "cors" };
 enum RequestCredentials { "omit", "same-origin", "include" };
 
 [
     Constructor(RequestInfo input, optional Dictionary requestInitDict),
     ConstructorCallWith=ExecutionContext,
-    RuntimeEnabled=ServiceWorker,
-    Exposed=ServiceWorker,
+    Exposed(Window GlobalFetch, DedicatedWorker GlobalFetch, SharedWorker GlobalFetch, ServiceWorker ServiceWorker),
     RaisesException=Constructor,
     ActiveDOMObject,
     GarbageCollected,
     TypeChecking=Interface,
 ] interface Request {
     readonly attribute ByteString method;
     readonly attribute USVString url;
     readonly attribute Headers headers;
 
     readonly attribute DOMString referrer;
     readonly attribute RequestMode mode;
     readonly attribute RequestCredentials credentials;
 
     [RaisesException] Request clone();
 
     // FIXME: Implement the following:
     // readonly attribute RequestContext context;
 };
 
 Request implements Body;