Move paint invalidation after compositing update

LayoutTests/fast/repaint/window-resize-background-image-fixed-centered-expected.txt

 {
   "bounds": [200, 300],
   "children": [
     {
       "bounds": [200, 300],
       "contentsOpaque": true,
       "drawsContent": true,
       "repaintRects": [
-        [0, 0, 200, 200],
+        [0, 0, 200, 300],
         [0, 0, 200, 200]
       ]
     }
   ]
 }
 {
   "bounds": [300, 300],
   "children": [
     {
       "bounds": [300, 300],
       "contentsOpaque": true,
       "drawsContent": true,
       "repaintRects": [
-        [0, 0, 200, 300],
+        [0, 0, 300, 300],
         [0, 0, 200, 300]
       ]
     }
   ]
 }
 {
   "bounds": [300, 250],
   "children": [
     {
       "bounds": [300, 250],
@@ skipping 14 matching lines @@
       "contentsOpaque": true,
       "drawsContent": true,
       "repaintRects": [
         [0, 0, 300, 250],
         [0, 0, 250, 250]
       ]
     }
   ]
 }