Use Web IDL Union types in Service Worker's Cache interface

Source/modules/serviceworkers/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
 
+typedef (Request or USVString) RequestInfo;
+
 [
     GarbageCollected,
     Exposed=ServiceWorker,
     RuntimeEnabled=ServiceWorkerCache,
     TypeChecking=Interface,
 ] interface Cache {
-  // FIXME: Blink doesn't support union types, we use overrides instead. See http://crbug.com/240176
+    [CallWith=ScriptState, RaisesException] Promise match(RequestInfo request, optional CacheQueryOptions options);
 
-  // [CallWith=ScriptState] Promise match((Request or USVString) request, optional CacheQueryOptions options);
-  [CallWith=ScriptState] Promise match(Request request, optional CacheQueryOptions options);
-  [CallWith=ScriptState, RaisesException] Promise match(USVString request, optional CacheQueryOptions options);
+    // FIXME: Implement matchAll(): http://crbug.com/428363
+    // FIXME: First argument of matchAll() should be optional: http://crbug.com/425459
+    // [CallWith=ScriptState, RaisesException] Promise matchAll(RequestInfo request, optional CacheQueryOptions options);
 
-  // FIXME: Implement matchAll(): http://crbug.com/428363
-  // FIXME: First argument of matchAll() should be optional: http://crbug.com/425459
-  // [CallWith=ScriptState] Promise matchAll((Request or USVString) request, optional CacheQueryOptions options);
-  // [CallWith=ScriptState] Promise matchAll(Request request, optional CacheQueryOptions options);
-  // [CallWith=ScriptState, RaisesException] Promise matchAll(USVString request, optional CacheQueryOptions options);
+    // FIXME: Implement add(): http://crbug.com/427652
+    // [CallWith=ScriptState, RaisesException] Promise add(RequestInfo request);
 
-  // FIXME: Implement add(): http://crbug.com/427652
-  // [CallWith=ScriptState] Promise add((Request or USVString) request);
-  // [CallWith=ScriptState] Promise add(Request request);
-  // [CallWith=ScriptState, RaisesException] Promise add(USVString request);
+    // FIXME: Implement addAll(): http://crbug.com/427652
+    // FIXME: Sequences of Unions are not yet supported, instead bind a generic type. http://crbug.com/240176
+    // [CallWith=ScriptState] Promise addAll(sequence<RequestInfo> requests);
+    // [CallWith=ScriptState] Promise addAll(sequence<any> requests);
 
-  // FIXME: Implement addAll(): http://crbug.com/427652
-  // FIXME: The lack of union type support together with the sequence mean we can't use overrides here, instead
-  // bind a generic type.
-  // [CallWith=ScriptState] Promise addAll(sequence<Request or USVString> requests);
-  // [CallWith=ScriptState] Promise addAll(sequence<any> requests);
-
-  // [CallWith=ScriptState] Promise put((Request or USVString) request, Response response);
-  [CallWith=ScriptState] Promise put(Request request, Response response);
-  [CallWith=ScriptState, RaisesException] Promise put(USVString request, Response response);
-
-  // [CallWith=ScriptState] Promise delete((Request or USVString) request, optional CacheQueryOptions options);
-  [CallWith=ScriptState, ImplementedAs=deleteFunction] Promise delete(Request request, optional CacheQueryOptions options);
-  [CallWith=ScriptState, ImplementedAs=deleteFunction, RaisesException] Promise delete(USVString request, optional CacheQueryOptions options);
-
-  // [CallWith=ScriptState] Promise keys(optional (Request or USVString) request, optional CacheQueryOptions options);
-  [CallWith=ScriptState] Promise keys(optional Request request, optional CacheQueryOptions options);
-  [CallWith=ScriptState, RaisesException] Promise keys(USVString request, optional CacheQueryOptions options);
+    [CallWith=ScriptState, RaisesException] Promise put(RequestInfo request, Response response);
+    [CallWith=ScriptState, ImplementedAs=deleteFunction, RaisesException] Promise delete(RequestInfo request, optional CacheQueryOptions options);
+    [CallWith=ScriptState, RaisesException] Promise keys(optional RequestInfo request, optional CacheQueryOptions options);
 };