AccumulatedVisualContext Tree:
  [0] transform=[1,0,0,1,0,0] origin=(0,0) (ViewportPaintable(Viewport<#document>))
    [1] scroll_frame_id=1 (PaintableWithLines(BlockContainer<PRE>#out))
      [2] clip=[9,9 104x18] (PaintableWithLines(BlockContainer<DIV>))
        [3] clip=[11,10 100x16]

DisplayList:
SaveLayer@0
  CompositorWheelHitTestTarget@0 target_scroll_frame_index=0 rect=[0,0 800x600]
  CompositorWheelHitTestTarget@1 target_scroll_frame_index=0 rect=[0,0 800x41]
  CompositorWheelHitTestTarget@1 target_scroll_frame_index=0 rect=[8,8 784x20]
  CompositorWheelHitTestTarget@1 target_scroll_frame_index=0 rect=[8,8 784x20]
  CompositorWheelHitTestTarget@1 target_scroll_frame_index=0 rect=[8,8 106x20]
  FillRect@1 rect=[8,8 106x20] color=rgb(255, 255, 255)
  FillPath@1 path_bounding_rect=[8,8 106x20]
  CompositorWheelHitTestTarget@2 target_scroll_frame_index=0 rect=[11,10 100x16]
  CompositorWheelHitTestTarget@2 target_scroll_frame_index=0 rect=[11,10 100x16]
  DrawGlyphRun@3 rect=[11,10 37x16] translation=[11,22.796875] color=rgb(0, 0, 0)
  FillRect@3 rect=[11,10 1x16] color=rgb(0, 0, 0)
  FillPath@1 path_bounding_rect=[6,6 110x24]
Restore@0