This test ensures that a stacking context overflow-scroll div's unclipped descendant gets its own composited layer, which is correctly parented under the overflow-div's composited layer.

(GraphicsLayer
  (bounds 1496.00 585.00)
  (children 1
    (GraphicsLayer
      (bounds 1496.00 585.00)
      (contentsOpaque 1)
      (drawsContent 1)
      (children 1
        (GraphicsLayer
          (position 28.00 20.00)
          (bounds 202.00 202.00)
          (drawsContent 1)
          (children 4
            (GraphicsLayer
              (position 1.00 1.00)
              (bounds 185.00 185.00)
              (children 1
                (GraphicsLayer
                  (bounds 190.00 185.00)
                  (drawsContent 1)
                  (children 1
                    (GraphicsLayer
                      (position 10.00 139.00)
                      (bounds 180.00 90.00)
                      (contentsOpaque 1)
                    )
                  )
                )
              )
            )
            (GraphicsLayer
              (position 1.00 186.00)
              (bounds 185.00 15.00)
              (drawsContent 1)
            )
            (GraphicsLayer
              (position 186.00 1.00)
              (bounds 15.00 185.00)
              (drawsContent 1)
            )
            (GraphicsLayer
              (position 186.00 186.00)
              (bounds 15.00 15.00)
              (drawsContent 1)
            )
          )
        )
      )
    )
  )
)