Get rid of a lot of () for getters.

runtime/lib/weak_property.dart

 // Copyright (c) 2012, 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 _WeakProperty {
   factory _WeakProperty(key, value) => _new(key, value);
 
-  get key() => _getKey();
-  get value() => _getValue();
+  get key => _getKey();
+  get value => _getValue();
   set value(value) => _setValue(value);
 
   static _WeakProperty _new(key, value) native "WeakProperty_new";
 
   _getKey() native "WeakProperty_getKey";
   _getValue() native "WeakProperty_getValue";
   _setValue(value) native "WeakProperty_setValue";
 }