Fix unittests

LayoutTests/platform/mac/virtual/software/compositing/tiling/huge-layer-with-layer-children-resize-expected.txt

 The yellow box should be 500 x 500 on startup. Then it should stretch to be 500 x 5000, then shrink back down to 500 x 500. This tests that we can resize to a huge layer and back again and still maintain integrity of the layer tree.
 
 First (small layer):
 (GraphicsLayer
   (bounds 785.00 611.00)
   (children 1
     (GraphicsLayer
       (bounds 785.00 611.00)
       (contentsOpaque 1)
       (drawsContent 1)
@@ skipping 95 matching lines @@
               (drawsContent 1)
               (backgroundColor #0000FF)
             )
           )
         )
       )
     )
   )
 )