Reapply remove setTimeout, take 3.

tests/html/microtask_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 microtask_;
 import '../../pkg/unittest/lib/unittest.dart';
 import '../../pkg/unittest/lib/html_config.dart';
+import 'dart:async';
 import 'dart:html';
 
 main() {
   useHtmlConfiguration();
 
   test('setImmediate', () {
     var timeoutCalled = false;
     var rafCalled = false;
     var immediateCalled = false;
 
-    window.setTimeout(expectAsync0(() {
+    Timer.run(expectAsync0(() {
       timeoutCalled = true;
       expect(immediateCalled, true);
-    }), 0);
+    }));
 
 
     window.requestAnimationFrame((_) {
       rafCalled = true;
     });
 
     window.setImmediate(expectAsync0(() {
       expect(timeoutCalled, false);
       expect(rafCalled, false);
       immediateCalled = true;
     }));
     expect(immediateCalled, false);
   });
 }