anchor.diff:    EventListener _onErrorClosure;
   
     bool _queuedToRun = false;
  +
  +  /** Whether a test is currently being executed by [runTest]. */
  +  bool _testIsRunning = false;
   
     // TODO(sigmund): remove isLayoutTest argument after converting all DOM tests
     // to use the named constructor below.
  
positive.code:     _uncaughtError = false;
      _callbacksCalled = 0;
      try {
        (testCase.test)();
        if (!_uncaughtError) {
          if (testCase.callbacks == _callbacksCalled) {
  
negative.code:       _uncaughtError = true;
      } else if (_callbacksCalled == testCase.callbacks) {
        testCase.recordSuccess();
        if (!_testIsRunning) {
          _currentTest++;
          _nextBatch();
        }
      }
    }
  
  