Issue repaints when offsetFromRenderer changes for any squashed layer.

LayoutTests/compositing/squashing/resize-squashing-layer-that-needs-full-repaint-expected.txt

+CONSOLE MESSAGE: line 22: remove
 (GraphicsLayer
   (bounds 800.00 600.00)
   (children 1
     (GraphicsLayer
       (bounds 800.00 600.00)
       (contentsOpaque 1)
       (drawsContent 1)
       (children 1
         (GraphicsLayer
           (children 2
             (GraphicsLayer
               (position 8.00 8.00)
-              (bounds 200.00 200.00)
-              (contentsOpaque 1)
-              (drawsContent 1)
-              (backgroundColor #ADD8E6)
+              (bounds 500.00 500.00)
             )
             (GraphicsLayer
-              (position 50.00 50.00)
-              (bounds 50.00 50.00)
+              (position 55.00 55.00)
+              (bounds 500.00 500.00)
               (drawsContent 1)
               (repaint rects
+                (rect 55.00 55.00 500.00 500.00)
+                (rect 0.00 0.00 500.00 500.00)

[chrishtr, 2014/06/12 23:49:37]

This second rect would not have been present but for my CL.

                 (rect 0.00 0.00 50.00 50.00)
-                (rect 0.00 0.00 40.00 40.00)
               )
             )
           )
         )
       )
     )
   )
 )