update elements and fix some bugs

test/iron_form_test.dart

 // Copyright (c) 2015, 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.
 @TestOn('browser')
 library polymer_elements.test.iron_form_test;
 
 import 'dart:async';
 import 'dart:html';
 import 'dart:js';
 import 'package:polymer_elements/iron_form.dart';
@@ skipping 169 matching lines @@
       form = fixture('FormGet');
 
       var submitted = false;
       form.on['iron-form-submit'].take(1).listen((_) {
         submitted = true;
       });
 
       form.on['iron-form-response'].take(1).listen((event) {
         expect(submitted, isTrue);
 
-        var response = new JsObject.fromBrowserObject(event)['detail'];
+        var response = convertToDart(event).detail.response;
         expect(response, isNotNull);
         expect(response is JsObject, isTrue);
         expect(response['success'], isTrue);
         done.complete();
       });
 
       form.submit();
       return done.future;
     });
 
     test('can submit with method=post', () {
       var done = new Completer();
       form = fixture('FormPost');
 
       var submitted = false;
       form.on['iron-form-submit'].take(1).listen((_) {
         submitted = true;
       });
 
       form.on['iron-form-response'].take(1).listen((event) {
         expect(submitted, isTrue);
-        var response = event.detail;
+        var response = convertToDart(event).detail.response;
         expect(response, isNotNull);
         expect(response is JsObject, isTrue);
         expect(response['success'], isTrue);
         done.complete();
       });
 
       form.submit();
       return done.future;
     }, skip: 'https://github.com/dart-lang/polymer_elements/issues/16');
 
     test('can relay errors', () {
       var done = new Completer();
       form = fixture('FormPost');
       form.action = "/responds_with_error";
 
       form.on['iron-form-error'].take(1).listen((event) {
         var error = convertToDart(event).detail;
 
         expect(error, isNotNull);
         expect(error is Map, isTrue);
         expect(error['error'], isNotNull);
         done.complete();
       });
 
       form.submit();
       return done.future;
     });
   });
 }