update elements and fix some bugs

test/iron_a11y_announcer_test.dart

Index: test/iron_a11y_announcer_test.dart
diff --git a/test/iron_a11y_announcer_test.dart b/test/iron_a11y_announcer_test.dart
index 1a3e414f9f21db2c355a607c27098eb82e4d060b..7fb1d06508125da66102d3cb03053d60cfed2e8f 100644
--- a/test/iron_a11y_announcer_test.dart
+++ b/test/iron_a11y_announcer_test.dart
@@ -6,6 +6,7 @@ library polymer_elements.test.iron_a11y_announcer_test;
 
 import 'dart:async';
 import 'dart:html';
+import 'dart:js';
 import 'package:polymer_elements/iron_a11y_announcer.dart';
 import 'package:web_components/web_components.dart';
 import 'package:test/test.dart';
@@ -21,9 +22,8 @@ main() async {
     });
 
     test('announces when there is an iron-announce event', () async {
-      var event = new CustomEvent('iron-announce',
-          canBubble: true, detail: {'text': 'foo'});
-      document.body.dispatchEvent(event);
+      announcer.fire('iron-announce',
+          detail: {'text': 'foo'}, node: document.body);
       // Text isn't set for 100ms
       await new Future.delayed(new Duration(milliseconds: 200), () {});
       expect(announcer.jsElement['_text'], 'foo');