Adding dart:indexed_db.

sdk/lib/html/templates/html/dart2js/impl_WorkerContext.darttemplate

Index: sdk/lib/html/templates/html/dart2js/impl_WorkerContext.darttemplate
diff --git a/sdk/lib/html/templates/html/impl/impl_WebSocket.darttemplate b/sdk/lib/html/templates/html/dart2js/impl_WorkerContext.darttemplate
similarity index 68%
copy from sdk/lib/html/templates/html/impl/impl_WebSocket.darttemplate
copy to sdk/lib/html/templates/html/dart2js/impl_WorkerContext.darttemplate
index 6fb4d40926334f9d23478b14244be4d782fc1db5..157b7915a42f21aae4ad43f8a449b4897f8838f1 100644
--- a/sdk/lib/html/templates/html/impl/impl_WebSocket.darttemplate
+++ b/sdk/lib/html/templates/html/dart2js/impl_WorkerContext.darttemplate
@@ -2,12 +2,14 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// WARNING: Do not edit - generated code.
-
 part of html;
 
 /// @domName $DOMNAME
 class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
-  factory $CLASSNAME(String url) => _$(CLASSNAME)FactoryProvider.create$CLASSNAME(url);
 $!MEMBERS
+
+  IdbFactory get indexedDB =>
+      JS('IdbFactory',
+         '#.indexedDB || #.webkitIndexedDB || #.mozIndexedDB',
+         this, this, this);
 }