Use 'field' syntax in dart:dom interfaces.

client/dom/generated/src/interface/SVGStringList.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.
 
 // WARNING: Do not edit - generated code.
 
 interface SVGStringList {
 
-  int get numberOfItems();
+  final int numberOfItems;
 
   String appendItem(String item);
 
   void clear();
 
   String getItem(int index);
 
   String initialize(String item);
 
   String insertItemBefore(String item, int index);
 
   String removeItem(int index);
 
   String replaceItem(String item, int index);
 }