anchor.diff:      if (!_dirty || _defunct)
         return;
   
  -    assert(_root != null);
  -    _sync(null, _root.parentNode, _root.nextSibling);
  +    assert(_host != null);
  +    _sync(null, _host, _insertionPoint);
     }
   
     void scheduleBuild() {
  
positive.code: }
  
  abstract class App extends Component {
    sky.Node _host = null;
    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);
        _notifyMountStatusChanged();
  
        sw.stop();
        if (_shouldLogRenderDuration)
          print("Initial build: ${sw.elapsedMicroseconds} microseconds");
      });
    }
  }
  
negative.code:   bool get _isBuilding => _currentlyBuilding == this;
    bool _dirty = true;
  
    sky.Node get _host => _root.parentNode;
    sky.Node get _insertionPoint => _root == null ? _root : _root.nextSibling;
  
    Node _built;
    final int _order;
    static int _currentOrder = 0;
  