Make getKeys, getValues getters (keys, values).

tests/html/js_interop_3_test.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
 
 #library('JsInterop3Test');
 #import('../../pkg/unittest/unittest.dart');
 #import('../../pkg/unittest/html_config.dart');
 #import('dart:html');
 #import('dart:isolate');
 
@@ skipping 13 matching lines @@
 """;
 
 main() {
   useHtmlConfiguration();
 
   test('js-to-dart', () {
     var fun1 = (message) {
       Expect.equals('Hello', message['a']);
       Expect.equals('World', message['b']);
       Expect.equals(42, message['c']);
-      Expect.equals(3, message.getKeys().length);
+      Expect.equals(3, message.keys.length);
       return 42;
     };
 
     var port1 = new ReceivePortSync();
     port1.receive(fun1);
     window.registerPort('fun1', port1.toSendPort());
 
     // TODO(vsm): Investigate why this needs to be called asynchronously.
     var done = expectAsync0(() {});
     var fun2 = (message) {
       Expect.equals(42, message);
       window.setTimeout(done, 0);
     };
 
     var port2 = new ReceivePortSync();
     port2.receive(fun2);
     window.registerPort('fun2', port2.toSendPort());
 
     injectSource(jsToDart);
   });
 }