frog: use type annotation in map and list literals

client/html/src/EventTargetWrappingImplementation.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // 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.
 
 class EventsImplementation implements Events {
   /* Raw event target. */
   var _ptr;
 
   Map<String, EventListenerList> _listenerMap;
 
   EventsImplementation._wrap(this._ptr) {
-    _listenerMap = <String, EventListenerList>{};
+    _listenerMap = <EventListenerList>{};
   }
 
   EventListenerList operator [](String type) {
     return _get(type.toLowerCase());
   }
   
   EventListenerList _get(String type) {
     return _listenerMap.putIfAbsent(type,
       () => new EventListenerListImplementation(_ptr, type));
   }
@@ skipping 86 matching lines @@
 
   EventTargetWrappingImplementation._wrap(ptr) : super._wrap(ptr);
 
   Events get on() {
     if (_on === null) {
       _on = new EventsImplementation._wrap(_ptr);
     }
     return _on;
   }
 }