Migrate dom tests to dart:html.

client/tests/client/dom/MessageEventTest.dart

Index: client/tests/client/dom/MessageEventTest.dart
diff --git a/client/tests/client/dom/MessageEventTest.dart b/client/tests/client/dom/MessageEventTest.dart
index 651ce5354e35b935003af842d91cc29734d82833..be802f2c7fa3a443d3eb65c9c3a04fc6ba785835 100644
--- a/client/tests/client/dom/MessageEventTest.dart
+++ b/client/tests/client/dom/MessageEventTest.dart
@@ -1,13 +1,13 @@
 #library('SerializedScriptValueTest');
 #import('../../../../lib/unittest/unittest.dart');
-#import('../../../../lib/unittest/dom_config.dart');
-#import('dart:dom');
+#import('../../../../lib/unittest/html_config.dart');
+#import('dart:html');
 
 main() {
-  useDomConfiguration();
+  useHtmlConfiguration();
 
   test('MessageEvent.initMessageEvent', () {
-      final event = document.createEvent('MessageEvent');
+      final event = document.$dom_createEvent('MessageEvent');
       event.initMessageEvent('type', false, true, 'data', 'origin', 'lastEventId', window, []);
       expect(event.type).equals('type');
       expect(event.bubbles).equals(false);