Merge 176880 "Properly repaint RenderLayer's descendants when it..."

LayoutTests/fast/repaint/repaint-descandant-on-ancestor-layer-move-expected.txt

 {
   "bounds": [800, 600],
   "children": [
     {
       "bounds": [800, 600],
       "contentsOpaque": true,
       "drawsContent": true,
       "repaintRects": [
         [428, 38, 300, 18],
         [408, 18, 300, 18],
         [28, 38, 300, 18],
         [8, 18, 300, 18]
       ]
     }
   ]
 }