Revert of [ServiceWorker] Make Response class better conformance with the spec.

Source/modules/serviceworkers/HeaderMapForEachCallback.idl

Index: Source/modules/serviceworkers/HeaderMapForEachCallback.idl
diff --git a/Source/modules/serviceworkers/HeaderMapForEachCallback.idl b/Source/modules/serviceworkers/HeaderMapForEachCallback.idl
new file mode 100644
index 0000000000000000000000000000000000000000..d6bbb8dfc96e0e4a3c1753d2b6bf38e427baea15
--- /dev/null
+++ b/Source/modules/serviceworkers/HeaderMapForEachCallback.idl
@@ -0,0 +1,8 @@
+// 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.
+
+callback interface HeaderMapForEachCallback {
+    [CallWith=ThisValue] boolean handleItem(DOMString value, DOMString key, HeaderMap map);
+    boolean handleItem(DOMString value, DOMString key, HeaderMap map);
+};