More rebaselines for r155279.

LayoutTests/platform/mac/compositing/force-compositing-mode/overflow-iframe-enter-compositing-expected.txt

 
 (GraphicsLayer
   (bounds 800.00 600.00)
   (children 1
     (GraphicsLayer
       (bounds 800.00 600.00)
       (contentsOpaque 1)
       (drawsContent 1)
       (children 1
         (GraphicsLayer
@@ skipping 18 matching lines @@
                             )
                           )
                         )
                       )
                     )
                   )
                 )
                 (GraphicsLayer
                   (position 0.00 135.00)
                   (bounds 135.00 15.00)
-                  (drawsContent 1)
                 )
                 (GraphicsLayer
                   (position 135.00 0.00)
                   (bounds 15.00 135.00)
-                  (drawsContent 1)
                 )
                 (GraphicsLayer
                   (position 135.00 135.00)
                   (bounds 15.00 15.00)
                   (drawsContent 1)
                 )
               )
             )
           )
         )
       )
     )
   )
 )