Reland "Unifies ScrollView and RenderLayer to use non-shi..."

LayoutTests/platform/chromium-linux/virtual/gpu/compositedscrolling/overflow/scrolling-without-painting-expected.txt

 (GraphicsLayer
   (bounds 800.00 600.00)
   (children 1
     (GraphicsLayer
       (bounds 800.00 600.00)
       (contentsOpaque 1)
       (children 1
         (GraphicsLayer
           (position 8.00 8.00)
           (bounds 202.00 202.00)
           (drawsContent 1)
           (children 4
             (GraphicsLayer
               (position 1.00 1.00)
-              (bounds 200.00 200.00)
+              (bounds 185.00 185.00)
               (children 1
                 (GraphicsLayer
                   (position 0.00 -25.00)
                   (bounds 185.00 1025.00)
                   (drawsContent 1)
                 )
               )
             )
             (GraphicsLayer
               (position 1.00 186.00)
@@ skipping 13 matching lines @@
               (bounds 15.00 15.00)
               (drawsContent 1)
             )
           )
         )
       )
     )
   )
 )