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] scroll_compensation(frame_id=1)

DisplayList:
SaveLayer@0
  CompositorWheelHitTestTarget@0 target_scroll_frame_index=1 rect=[0,0 800x600]
  CompositorScrollNode@0 scroll_frame_index=1 parent_scroll_frame_index=0 scrollport_rect=[0,0 800x600] max_scroll_offset=[0,613] is_viewport=true
  CompositorWheelHitTestTarget@1 target_scroll_frame_index=1 rect=[0,0 800x1213]
  Save@1
    PaintLinearGradient@2 rect=[0,0 800x600]
  Restore@1
  CompositorWheelHitTestTarget@1 target_scroll_frame_index=1 rect=[0,13 800x1200]
Restore@0

