Don't repaint squashed, fixed position layers during scrolling

LayoutTests/compositing/repaint/scroll-fixed-squahed-layer-expected.txt

Index: LayoutTests/compositing/repaint/scroll-fixed-squahed-layer-expected.txt
diff --git a/LayoutTests/compositing/squashing/tricky-element-removal-crash-expected.txt b/LayoutTests/compositing/repaint/scroll-fixed-squahed-layer-expected.txt
similarity index 64%
copy from LayoutTests/compositing/squashing/tricky-element-removal-crash-expected.txt
copy to LayoutTests/compositing/repaint/scroll-fixed-squahed-layer-expected.txt
index de9967ce278048e225916146c2b74c7245b46d2d..63d7a8dfb1759481d752b8d6c82b710387b4d1b1 100644
--- a/LayoutTests/compositing/squashing/tricky-element-removal-crash-expected.txt
+++ b/LayoutTests/compositing/repaint/scroll-fixed-squahed-layer-expected.txt
@@ -1,23 +1,23 @@
 {
-  "bounds": [800, 600],
+  "bounds": [785, 2016],
   "children": [
     {
-      "bounds": [800, 600],
+      "bounds": [785, 2016],
       "contentsOpaque": true,
       "drawsContent": true,
       "children": [
         {
           "children": [
             {
-              "position": [8, 8],
+              "position": [100, 200],
               "bounds": [200, 200],
               "contentsOpaque": true,
               "drawsContent": true,
-              "backgroundColor": "#FA8072"
+              "backgroundColor": "#ADD8E6"
             },
             {
-              "position": [8, 8],
-              "bounds": [100, 100],
+              "position": [100, 250],
+              "bounds": [200, 200],
               "drawsContent": true
             }
           ]