Get rid of a lot of () for getters.

lib/html/src/MutationEventWrappingImplementation.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 MutationEventWrappingImplementation extends EventWrappingImplementation implements MutationEvent {
   MutationEventWrappingImplementation._wrap(ptr) : super._wrap(ptr);
 
   factory MutationEventWrappingImplementation(String type, Node relatedNode,
       String prevValue, String newValue, String attrName, int attrChange,
       [bool canBubble = true, bool cancelable = true]) {
     final e = dom.document.createEvent("MutationEvent");
     e.initMutationEvent(type, canBubble, cancelable,
         LevelDom.unwrap(relatedNode), prevValue, newValue, attrName,
         attrChange);
     return LevelDom.wrapMutationEvent(e);
   }
 
-  int get attrChange() => _ptr.attrChange;
+  int get attrChange => _ptr.attrChange;
 
-  String get attrName() => _ptr.attrName;
+  String get attrName => _ptr.attrName;
 
-  String get newValue() => _ptr.newValue;
+  String get newValue => _ptr.newValue;
 
-  String get prevValue() => _ptr.prevValue;
+  String get prevValue => _ptr.prevValue;
 
-  Node get relatedNode() => LevelDom.wrapNode(_ptr.relatedNode);
+  Node get relatedNode => LevelDom.wrapNode(_ptr.relatedNode);
 }