update elements and fix some bugs

test/iron_selector_activate_event_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_selector_activate_event_test;
 
 import 'dart:async';
 import 'dart:html';
 import 'package:polymer_interop/polymer_interop.dart';
 import 'package:polymer_elements/iron_selector.dart';
@@ skipping 94 matching lines @@
       // attach iron-activate listener
       s.on['iron-activate'].take(1).listen((event) {
         event = convertToDart(event);
         event.preventDefault();
       });
       // select Item 2
       s.children[2].dispatchEvent(new CustomEvent('tap', canBubble: true));
       // shouldn't got selected since we preventDefault in iron-activate
       expect(s.selected, '0');
     });
+    
+    test('activates after detach and re-attach', () {
+      // Detach and re-attach
+      var parent = s.parentNode;
+      s.remove();
+      parent.append(s);
+      
+      // select Item 2
+      s.children[2].dispatchEvent(new CustomEvent('tap', canBubble: true));
+      expect(s.selected, 2);
+    });
   });
 }