Use 'field' syntax in dart:dom interfaces.

client/dom/generated/src/interface/HTMLCanvasElement.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 HTMLCanvasElement extends HTMLElement {
 
-  int get height();
+  int height;
 
-  void set height(int value);
-
-  int get width();
-
-  void set width(int value);
+  int width;
 
   Object getContext(String contextId);
 
   String toDataURL(String type);
 }