Remove use of deprecated test methods (asynctTest/callbackDone/expectThrows).

dom/Workers.dart

 #import('../../../../../dart/pkg/unittest/lib/unittest.dart');
 #import('../../../../../dart/pkg/unittest/lib/html_config.dart');
 #import('dart:html');
 
 main() {
   useHtmlConfiguration(true);
 
-  asyncTest('Workers minimal', 1, () {
+  test('Workers minimal', () {
     // FIXME: once we decide how Workers and Dart go together, this may become pure
     // Dart test.
     final worker = new Worker('resources/pong.js');
     worker.onError.listen((error) => Expect.fail('error: $error'));
-    worker.onMessage.listen((event) {
+    worker.onMessage.listen(expectAsync1((event) {
         Expect.equals('I am fine, thank you.', event.data);
-        callbackDone();
-    });
+    }));
     worker.postMessage('How do you do?');
   });
 }