Revert "See also webkit.org/b/113415"

LayoutTests/platform/win/virtual/softwarecompositing/overflow/do-not-opt-non-stacking-context-descendants-into-composited-scrolling-expected.txt

 This test ensures that the descendants of children of non-stacking context overflow-scroll divs do not get promoted needlessly. Only the immediate child of an overflow-scroll div, or an unclipped descendant, need to be promoted.
 
 (GraphicsLayer
   (bounds 1832.00 1682.00)
   (children 1
     (GraphicsLayer
       (bounds 1832.00 1682.00)
       (contentsOpaque 1)
       (drawsContent 1)
       (children 4
         (GraphicsLayer
           (position 28.00 320.00)
           (bounds 402.00 402.00)
           (drawsContent 1)
           (children 4
             (GraphicsLayer
               (position 1.00 1.00)
               (bounds 385.00 385.00)
               (children 1
                 (GraphicsLayer
-                  (bounds 385.00 950.00)
+                  (bounds 385.00 940.00)
                 )
               )
             )
             (GraphicsLayer
               (position 1.00 386.00)
               (bounds 385.00 15.00)
               (drawsContent 1)
             )
             (GraphicsLayer
               (position 386.00 1.00)
@@ skipping 34 matching lines @@
               (contentsOpaque 1)
             )
           )
         )
       )
     )
   )
 )