Get rid of a lot of () for getters.

lib/html/src/CompositionEventWrappingImplementation.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 CompositionEventWrappingImplementation extends UIEventWrappingImplementation implements CompositionEvent {
   CompositionEventWrappingImplementation._wrap(ptr) : super._wrap(ptr);
 
   factory CompositionEventWrappingImplementation(String type, Window view,
       String data, [bool canBubble = true, bool cancelable = true]) {
     final e = dom.document.createEvent("CompositionEvent");
     e.initCompositionEvent(type, canBubble, cancelable, LevelDom.unwrap(view),
         data);
     return LevelDom.wrapCompositionEvent(e);
   }
 
-  String get data() => _ptr.data;
+  String get data => _ptr.data;
 }