Add all dart:html tests from the sdk to test/codegen.

test/codegen/lib/html/text_event_test.dart

+// Copyright (c) 2011, 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 text_event_test;
+import "package:expect/expect.dart";
+import 'package:unittest/unittest.dart';
+import 'package:unittest/html_config.dart';
+import 'dart:html';
+
+import 'event_test.dart';
+
+main() {
+  useHtmlConfiguration();
+
+  eventTest('TextEvent', () => new TextEvent('foo', view: window, data: 'data'),
+      (ev) { expect(ev.data, 'data'); });
+}