step 1 in making unittest platform independent.

samples/tests/samples/src/swarm/SwarmTest.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('swarm_tests');
 
 #import('dart:html');
 #import('../../../../swarm/swarmlib.dart');
 #import('../../../../ui_lib/base/base.dart');
 #import('../../../../ui_lib/view/view.dart');
@@ skipping 27 matching lines @@
     final feed = article.dataSource;
     return {
       'section': CollectionUtils.find(swarm.sections,
           (s) => s.feeds.indexOf(feed, 0) >= 0).id,
       'feed': feed.id,
       'article': article.id
     };
   }
 
   asyncTest('BackButton', 1, () {
-    serialInvokeAsync([() {
+    _serialInvokeAsync([() {
       Expect.equals(null, swarm.frontView.storyView); // verify initial state
 
       // Make sure we've transitioned to the section
       // In the real app, this isn't needed because ConveyorView fires the
       // transition end event before we can click a story.
       SectionView section = getView(swarm.sections[0]);
       section.showSources();
     }, 
     () {
       final item = swarm.sections[0].feeds[2].articles[1];
@@ skipping 71 matching lines @@
   void expectHistory(List<Map<String, String>> entries) {
     Expect.equals(entries.length, history.length);
     for (int i = 0; i < entries.length; i++) {
       Map e = entries[i];
       Map h = history[i];
       Expect.equals(e['article'], h['article']);
     }
     clearHistory();
   }
 }
+
+void _serialInvokeAsync(List closures) {
+  final length = closures.length;
+  if (length > 0) {
+    int i = 0;
+    void invokeNext() {
+      closures[i]();
+      i++;
+      if (i < length) {
+        window.setTimeout(invokeNext, 0);
+      }
+    }
+    window.setTimeout(invokeNext, 0);
+  }
+}