Issue repaints before and after changing the squashing assignment of a RenderLayer.

LayoutTests/compositing/squashing/add-remove-squashed-layers-expected.txt

Index: LayoutTests/compositing/squashing/add-remove-squashed-layers-expected.txt
diff --git a/LayoutTests/compositing/squashing/add-remove-squashed-layers-expected.txt b/LayoutTests/compositing/squashing/add-remove-squashed-layers-expected.txt
index 88653bed51b3c001ba047ab2d895d1208899aa96..ce78e7591ec7ec61f1ba9b842789def17bd02aff 100644
--- a/LayoutTests/compositing/squashing/add-remove-squashed-layers-expected.txt
+++ b/LayoutTests/compositing/squashing/add-remove-squashed-layers-expected.txt
@@ -39,6 +39,7 @@ CASE 2, overlap3 gets added:
       (drawsContent 1)
       (repaint rects
         (rect 300.00 300.00 100.00 100.00)
+        (rect 300.00 300.00 100.00 100.00)

[chrishtr, 2014/06/02 20:16:24]

Repaint for overlap3 when getting added to the squashing layer.

       )
       (children 1
         (GraphicsLayer
@@ -55,10 +56,10 @@ CASE 2, overlap3 gets added:
               (bounds 260.00 260.00)
               (drawsContent 1)
               (repaint rects
+                (rect 160.00 160.00 20.00 20.00)

[chrishtr, 2014/06/02 20:16:24]

The actual rect generated is (160 160 260 60), after assigning overlap3 to the
squashing layer.
This is clipped to the (180, 180) bounds of the  squashing graphics layer at the
time of the invalidation; the squashing layer is subsequently changed to bounds
of (260, 260).
It's an example of incorrect repaint rects due to trying to do this update
during
compositing update, as opposed to after it is done.

                 (rect 140.00 140.00 40.00 40.00)
                 (rect 80.00 80.00 100.00 100.00)
                 (rect 0.00 0.00 100.00 100.00)
-                (rect 0.00 0.00 100.00 100.00)
               )
             )
           )
@@ -142,6 +143,7 @@ CASE 5, overlap2 gets added back:
       (drawsContent 1)
       (repaint rects
         (rect 220.00 220.00 100.00 100.00)
+        (rect 220.00 220.00 100.00 100.00)

[chrishtr, 2014/06/02 20:16:24]

This and the ones below are the same situation as above.

       )
       (children 1
         (GraphicsLayer
@@ -161,6 +163,7 @@ CASE 5, overlap2 gets added back:
                 (rect 0.00 0.00 100.00 100.00)
                 (rect 0.00 0.00 100.00 100.00)
                 (rect 0.00 0.00 100.00 100.00)
+                (rect 0.00 0.00 20.00 20.00)
               )
             )
           )
@@ -179,6 +182,7 @@ CASE 6, overlap1 gets added back, and overlap3 gets removed:
       (drawsContent 1)
       (repaint rects
         (rect 140.00 140.00 100.00 100.00)
+        (rect 140.00 140.00 100.00 100.00)
       )
       (children 1
         (GraphicsLayer
@@ -200,6 +204,7 @@ CASE 6, overlap1 gets added back, and overlap3 gets removed:
                 (rect 0.00 0.00 100.00 100.00)
                 (rect 0.00 0.00 100.00 100.00)
                 (rect 0.00 0.00 20.00 20.00)
+                (rect 0.00 0.00 20.00 20.00)
               )
             )
           )