anchor.diff:  
     _dirtyComponents.clear();
     _renderScheduled = false;
  +
     sw.stop();
  -  print("Render took ${sw.elapsedMicroseconds} microseconds");
  +  if (_shouldLogRenderDuration)
  +    print("Render took ${sw.elapsedMicroseconds} microseconds");
   }
   
   void _scheduleComponentForRender(Component c) {
  
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:     _className = style == null ? '': style._className;
      _children = children == null ? _emptyList : children;
  
      if (_isInCheckedMode) {
        _debugReportDuplicateIds();
      }
    }
  