[polymer.dart] fix *Changed observers inheriting

pkg/polymer/test/events_test.dart

 // Copyright (c) 2013, 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 polymer.test.web.events_test;
 
 import 'dart:html';
 import 'package:polymer/polymer.dart';
 import 'package:unittest/html_config.dart';
 import 'package:unittest/unittest.dart';
@@ skipping 11 matching lines @@
 @CustomTag("test-a")
 class TestA extends PolymerElement {
   TestA.created() : super.created();
 
   List clicks = [];
   void clickHandler() {
     clicks.add('host click on: $localName (id $id)');
   }
 }
 
+@reflectable
+class TestBase extends PolymerElement {
+  TestBase.created() : super.created();
+
+  List clicks = [];
+  void clickHandler(e) {
+    clicks.add('local click under $localName (id $id) on ${e.target.id}');
+  }
+}
+
+@CustomTag("test-c")
+class TestC extends TestBase {
+  TestC.created() : super.created();
+}
+
 main() {
   initPolymer();
   useHtmlConfiguration();
 
   setUp(() => Polymer.onReady);
 
   test('host event', () {
     // Note: this test is currently the only event in
     // polymer/test/js/events.js at commit #7936ff8
     var testA = query('#a');
     expect(testA.clicks, isEmpty);
     testA.click();
     expect(testA.clicks, ['host click on: test-a (id a)']);
   });
 
   test('local event', () {
     var testB = query('#b');
     expect(testB.clicks, isEmpty);
     testB.click();
     expect(testB.clicks, []);
     var b1 = testB.shadowRoot.query('#b-1');
     b1.click();
     expect(testB.clicks, []);
     var b2 = testB.shadowRoot.query('#b-2');
     b2.click();
     expect(testB.clicks, ['local click under test-b (id b) on b-2']);
   });
+
+  test('event on superclass', () {
+    var testC = query('#c');
+    expect(testC.clicks, isEmpty);
+    testC.click();
+    expect(testC.clicks, []);
+    var c1 = testC.shadowRoot.query('#c-1');
+    c1.click();
+    expect(testC.clicks, []);
+    var c2 = testC.shadowRoot.query('#c-2');
+    c2.click();
+    expect(testC.clicks, ['local click under test-c (id c) on c-2']);
+  });
 }