Get rid of a lot of () for getters.

lib/html/src/PageTransitionEventWrappingImplementation.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 PageTransitionEventWrappingImplementation extends EventWrappingImplementation implements PageTransitionEvent {
   PageTransitionEventWrappingImplementation._wrap(ptr) : super._wrap(ptr);
 
   factory PageTransitionEventWrappingImplementation(String type,
       [bool canBubble = true, bool cancelable = true,
       bool persisted = false]) {
     final e = dom.document.createEvent("PageTransitionEvent");
     e.initPageTransitionEvent(type, canBubble, cancelable, persisted);
     return LevelDom.wrapPageTransitionEvent(e);
   }
 
-  bool get persisted() => _ptr.persisted;
+  bool get persisted => _ptr.persisted;
 }