Make squashing work with subpixel layout

LayoutTests/compositing/squashing/squash-transform-repainting-transformed-child-expected.txt

Index: LayoutTests/compositing/squashing/squash-transform-repainting-transformed-child-expected.txt
diff --git a/LayoutTests/compositing/squashing/squash-transform-repainting-transformed-child-expected.txt b/LayoutTests/compositing/squashing/squash-transform-repainting-transformed-child-expected.txt
index 97a0a78a25fee5d453ed2aadf80f4ae62ffd34f6..389ce8bdb52a2c07cb7d8732a310d8883043e3f9 100644
--- a/LayoutTests/compositing/squashing/squash-transform-repainting-transformed-child-expected.txt
+++ b/LayoutTests/compositing/squashing/squash-transform-repainting-transformed-child-expected.txt
@@ -17,8 +17,8 @@ CASE 1, original layer tree
               (backgroundColor #0000FF)
             )
             (GraphicsLayer
-              (position 5.00 5.00)
-              (bounds 275.09 275.09)
+              (position 4.00 4.00)
+              (bounds 276.00 276.00)
               (drawsContent 1)
             )
           )
@@ -46,13 +46,13 @@ CASE 2, hovering over the outer div
               (backgroundColor #0000FF)
             )
             (GraphicsLayer
-              (position 5.00 5.00)
-              (bounds 275.09 275.09)
+              (position 4.00 4.00)
+              (bounds 276.00 276.00)
               (drawsContent 1)
               (repaint rects
-                (rect 0.00 0.00 131.00 131.00)
-                (rect 0.00 0.00 131.00 131.00)
-                (rect 0.00 0.00 131.00 131.00)
+                (rect 0.00 0.00 132.00 132.00)
+                (rect 0.00 0.00 132.00 132.00)
+                (rect 0.00 0.00 132.00 132.00)
               )
             )
           )
@@ -80,16 +80,16 @@ CASE 3, hovering over the inner div
               (backgroundColor #0000FF)
             )
             (GraphicsLayer
-              (position 5.00 5.00)
-              (bounds 275.09 275.09)
+              (position 4.00 4.00)
+              (bounds 276.00 276.00)
               (drawsContent 1)
               (repaint rects
-                (rect 0.00 0.00 131.00 131.00)
-                (rect 0.00 0.00 131.00 131.00)
-                (rect 0.00 0.00 131.00 131.00)
-                (rect 17.00 20.00 87.00 87.00)
-                (rect 17.00 20.00 87.00 87.00)
-                (rect 17.00 20.00 87.00 87.00)
+                (rect 0.00 0.00 132.00 132.00)
+                (rect 0.00 0.00 132.00 132.00)
+                (rect 0.00 0.00 132.00 132.00)
+                (rect 18.00 21.00 87.00 87.00)
+                (rect 18.00 21.00 87.00 87.00)
+                (rect 18.00 21.00 87.00 87.00)
               )
             )
           )