anchor.diff:  }
   
   /// An element that uses a [RenderObjectWidget] as its configuration.
  +///
  +/// [RenderObjectElement] objects have an associated [RenderObject] widget in
  +/// the render tree, which handles concrete operations like laying out,
  +/// painting, and hit testing.
  +///
  +/// Contrast with [ComponentElement].
   abstract class RenderObjectElement extends BuildableElement {
     /// Creates an element that uses the given widget as its configuration.
     RenderObjectElement(RenderObjectWidget widget) : super(widget);
  
positive.code:     Timeline.startSync('Build');
      try {
        _scheduledFlushDirtyElements = true;
        if (callback != null)
          callback();
        _dirtyElements.sort(_elementSort);
        _dirtyElementsNeedsResorting = false;
        int dirtyCount = _dirtyElements.length;
  
negative.code: ///
  /// Rather than creating a [RenderObject] directly, a [ComponentElement] creates
  /// [RenderObject]s indirectly by creating other [Element]s.
  ///
  /// Contrast with [RenderObjectElement].
  abstract class ComponentElement extends BuildableElement {
    /// Creates an element that uses the given widget as its configuration.
    ComponentElement(Widget widget) : super(widget);
  