Move Cache Storage API implementation to modules/cachestorage

Source/modules/serviceworkers/WindowCacheStorage.idl

Index: Source/modules/serviceworkers/WindowCacheStorage.idl
diff --git a/Source/modules/serviceworkers/WindowCacheStorage.idl b/Source/modules/serviceworkers/WindowCacheStorage.idl
deleted file mode 100644
index 7aadd81083018b278d1624eabf483d4e11ce9e59..0000000000000000000000000000000000000000
--- a/Source/modules/serviceworkers/WindowCacheStorage.idl
+++ /dev/null
@@ -1,11 +0,0 @@
-// Copyright 2015 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/#self-caches
-[
-    RuntimeEnabled=GlobalCacheStorage,
-    ImplementedAs=GlobalCacheStorage,
-] partial interface Window {
-    [Unforgeable, MeasureAs=GlobalCacheStorage, RuntimeEnabled=GlobalCacheStorage, RaisesException] readonly attribute CacheStorage caches;
-};