anchor.diff:  import 'dart:sky' as sky;
   import 'reflect.dart' as reflect;
   
  -bool _checkedMode;
  -
  -bool _debugWarnings() {
  +bool _initIsInCheckedMode() {
     void testFn(double i) {}
  -
  -  if (_checkedMode == null) {
  -    _checkedMode = false;
  -    try {
  -      testFn('not a double');
  -    } catch (ex) {
  -      _checkedMode = true;
  -    }
  -  }
  -
  -  return _checkedMode;
  -}
  +  try {
  +    testFn('not a double');
  +  } catch (ex) {
  +    return true;
  +  }
  +  return false;
  +}
  +
  +final bool _isInCheckedMode = _initIsInCheckedMode();
  +final bool _shouldLogRenderDuration = false;
   
   class EventHandler {
     final String type;
  
positive.code:     _className = style == null ? '': style._className;
      _children = children == null ? _emptyList : children;
  
      if (_debugWarnings()) {
        _debugReportDuplicateIds();
      }
    }
  
negative.code: 
    _dirtyComponents.clear();
    _renderScheduled = false;
  
    sw.stop();
    if (_shouldLogRenderDuration)
      print("Render took ${sw.elapsedMicroseconds} microseconds");
  }
  
  void _scheduleComponentForRender(Component c) {
  