anchor.diff:      DateTime end = new DateTime.now();
       int elapsed = end.difference(_testStarts[testCase.id]).inMilliseconds;
       if (testCase.stackTrace != null) {
  -      parentWindow.postMessage(
  +      _parentWindow.postMessage(
             _Message.text(_Message.STACK, elapsed, testCase.stackTrace), '*');
       }
  -    parentWindow.postMessage(
  +    _parentWindow.postMessage(
           _Message.text(testCase.result, elapsed, testCase.message), '*');
     }
     void onSummary(int passed, int failed, int errors, List<TestCase> results,
  
positive.code: import 'unittest.dart';
  
  /** The messages exchanged between parent and child. */
  
  class _Message {
    static const START = 'start';
    static const LOG = 'log';
  
negative.code:   void _handleMessage(MessageEvent e) {
      // Get the result, do any logging, then do a pass/fail.
      var msg = new _Message.fromString(e.data);
  
      if(msg == null) {
        return;
      }
      if (msg.messageType == _Message.LOG) {
        logMessage(e.data);
      } else if (msg.messageType == _Message.STACK) {
  