Have bindings layer assume and insist that all interface types are GCed.

third_party/WebKit/Source/modules/cachestorage/Cache.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.
 
 // See https://slightlyoff.github.io/ServiceWorker/spec/service_worker/index.html#cache
 
 [
-    GarbageCollected,
     Exposed=(Window,Worker),
 ] interface Cache {
     [CallWith=ScriptState, RaisesException] Promise<Response> match(RequestInfo request, optional CacheQueryOptions options);
     [CallWith=ScriptState, RaisesException] Promise<sequence<Response>> matchAll(optional RequestInfo request, optional CacheQueryOptions options);
     [CallWith=ScriptState, RaisesException] Promise<void> add(RequestInfo request);
     [CallWith=ScriptState, RaisesException] Promise<void> addAll(sequence<RequestInfo> requests);
     [CallWith=ScriptState, RaisesException] Promise<void> put(RequestInfo request, Response response);
     [CallWith=ScriptState, ImplementedAs=deleteFunction, RaisesException] Promise<boolean> delete(RequestInfo request, optional CacheQueryOptions options);
     [CallWith=ScriptState, RaisesException] Promise<sequence<Response>> keys(optional RequestInfo request, optional CacheQueryOptions options);
 };