Get rid of a lot of () for getters.

lib/html/src/PopStateEventWrappingImplementation.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 PopStateEventWrappingImplementation extends EventWrappingImplementation implements PopStateEvent {
   PopStateEventWrappingImplementation._wrap(ptr) : super._wrap(ptr);
 
   factory PopStateEventWrappingImplementation(String type, Object state,
       [bool canBubble = true, bool cancelable = true]) {
     final e = dom.document.createEvent("PopStateEvent");
     e.initPopStateEvent(type, canBubble, cancelable, state);
     return LevelDom.wrapPopStateEvent(e);
   }
 
-  String get state() => _ptr.state;
+  String get state => _ptr.state;
 }