anchor.diff:  
   abstract class App extends Component {
     sky.Node _host = null;
  -  App()
  -    : super(stateful: true) {
  -
  +  App() : super(stateful: true) {
       _host = sky.document.createElement('div');
       sky.document.appendChild(_host);
   
       new Future.microtask(() {
         Stopwatch sw = new Stopwatch()..start();
  +
         _sync(null, _host, null);
         assert(_root is sky.Node);
  +
         sw.stop();
  -      print("Initial render: ${sw.elapsedMicroseconds} microseconds");
  +      if (_shouldLogRenderDuration)
  +        print("Initial render: ${sw.elapsedMicroseconds} microseconds");
       });
     }
   }
  
positive.code: import 'dart:sky' as sky;
  import 'reflect.dart' as reflect;
  
  bool _checkedMode;
  
  bool _debugWarnings() {
    void testFn(double i) {}
  
    if (_checkedMode == null) {
      _checkedMode = false;
      try {
        testFn('not a double');
      } catch (ex) {
        _checkedMode = true;
      }
    }
  
    return _checkedMode;
  }
  
  class EventHandler {
    final String type;
  
negative.code: 
    _dirtyComponents.clear();
    _renderScheduled = false;
  
    sw.stop();
    if (_shouldLogRenderDuration)
      print("Render took ${sw.elapsedMicroseconds} microseconds");
  }
  
  void _scheduleComponentForRender(Component c) {
  