Non-composited scrolling div should invalidate when it has descendant paints to its backing

LayoutTests/compositing/squashing/invalidate-when-leaving-squashed-layer-expected.txt

 {
   "bounds": [800, 600],
   "children": [
     {
       "bounds": [800, 600],
       "contentsOpaque": true,
       "drawsContent": true,
       "children": [
         {
           "children": [
@@ skipping 15 matching lines @@
           ]
         },
         {
           "position": [50, 50],
           "bounds": [200, 200],
           "contentsOpaque": true,
           "drawsContent": true,
           "backgroundColor": "#ADD8E6",
           "repaintRects": [
             [0, 0, 200, 200],
-            [0, 0, 200, 200],
             [0, 0, 200, 200]
           ]
         }
       ]
     }
   ]
 }