Fix pixel snapping of clipLayers and their descendants

LayoutTests/compositing/repaint/should-not-repaint-composited-styles-expected.txt

Index: LayoutTests/compositing/repaint/should-not-repaint-composited-styles-expected.txt
diff --git a/LayoutTests/compositing/repaint/should-not-repaint-composited-styles-expected.txt b/LayoutTests/compositing/repaint/should-not-repaint-composited-styles-expected.txt
index 72664a438fed97cefefbdb0f80be02a7b42a85bb..fb22d06b49c3d64d104aa02040c77f9b1d1c841f 100644
--- a/LayoutTests/compositing/repaint/should-not-repaint-composited-styles-expected.txt
+++ b/LayoutTests/compositing/repaint/should-not-repaint-composited-styles-expected.txt
@@ -31,11 +31,9 @@ filter change with non-composited child
           (bounds 100.00 100.00)
           (children 1
             (GraphicsLayer
-              (position 0.00 -1.00)
               (bounds 100.00 100.00)
               (children 1
                 (GraphicsLayer
-                  (position 0.00 1.00)
                   (bounds 152.00 152.00)
                   (contentsOpaque 1)
                   (drawsContent 1)
@@ -116,11 +114,9 @@ filter change with non-composited child
           )
           (children 1
             (GraphicsLayer
-              (position 0.00 -1.00)
               (bounds 100.00 100.00)
               (children 1
                 (GraphicsLayer
-                  (position 0.00 1.00)
                   (bounds 152.00 152.00)
                   (contentsOpaque 1)
                   (drawsContent 1)
@@ -143,11 +139,9 @@ filter change with non-composited child
           (bounds 100.00 100.00)
           (children 1
             (GraphicsLayer
-              (position 0.00 -1.00)
               (bounds 100.00 100.00)
               (children 1
                 (GraphicsLayer
-                  (position 0.00 1.00)
                   (bounds 152.00 152.00)
                   (contentsOpaque 1)
                   (drawsContent 1)