anchor.diff:      
       window.requestAnimationFrame(
           (_) {
  -          _currentPeformance = perf - getPerformanceNow();
  +          _currentPeformance = getPerformanceNow() - perf;
             
             _animationFrameCompleter.complete();
  +          
  +          _animationFrameCompleter = null;
           }
       );
       
  -    final Future result = _animationFrameCompleter.future;
  -    
  -    result.whenComplete(() => _animationFrameCompleter = null);
  -    
  -    return result;
  +    _animationFrameFuture = _animationFrameCompleter.future;
  +    
  +    return _animationFrameFuture;
     }
     
     //---------------------------------
  
positive.code:       (window.performance != null) &&
        (window.performance.now != null)
      ) return window.performance.now();
      return .0;
    }
    
    void scheduleMethod(dynamic owner, Function method, List arguments, {bool forceSingleExecution: false}) {
  
negative.code:   static const String _PRIORITY = '';
    
    final Element _element;
    
    Map<String, String> _dirtyProperties;
    
    _ElementCSSMap(this._element) {
      _dirtyProperties = <String, String>{};
    }
    
    void finalize() {
      _dirtyProperties.forEach(
        (String propertyName, String propertyValue) => _element.style.setProperty(propertyName, propertyValue, _PRIORITY)
      );
      
      _dirtyProperties = <String, String>{};
    }
    
    void setProperty(String propertyName, String value) {
      _dirtyProperties[propertyName] = value;
    }
    
    String toString() => '$_element $_dirtyProperties';
  }