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

test/codegen/lib/html/async_test.dart

+library async_test;
+
+import 'package:unittest/unittest.dart';
+import 'package:unittest/html_config.dart';
+
+import 'dart:async';
+import 'dart:isolate';
+import 'dart:html';
+
+import 'async_oneshot.dart' as oneshot_test show main; 
+import 'async_periodictimer.dart' as periodictimer_test show main;
+import 'async_cancellingisolate.dart' as cancelling_test show main;
+
+oneshot(message) => oneshot_test.main(message.first, message.last);
+periodicTimerIsolate(message) =>
+    periodictimer_test.main(message.first, message.last);
+cancellingIsolate(message) => cancelling_test.main(message.first, message.last);
+
+main() {
+  useHtmlConfiguration();
+
+  test('one shot timer in pure isolate', () {
+    var response = new ReceivePort();
+    var remote = Isolate.spawn(oneshot,
+                               [['START'], response.sendPort]);
+    expect(remote.then((_) => response.first), completion('DONE'));
+  });
+
+  test('periodic timer in pure isolate', () {
+    var response = new ReceivePort();
+    var remote = Isolate.spawn(periodicTimerIsolate,
+                               [['START'], response.sendPort]);
+    expect(remote.then((_) => response.first), completion('DONE'));
+  });
+  
+  test('cancellation in pure isolate', () {
+    var response = new ReceivePort();
+    var remote = Isolate.spawn(cancellingIsolate,
+                               [['START'], response.sendPort]);
+    expect(remote.then((_) => response.first), completion('DONE'));
+  });
+}