Move selection invalidation to the invalidation phase

LayoutTests/platform/linux/fast/repaint/selection-partial-invalidation-between-blocks-expected.txt

 {
   "bounds": [800, 600],
   "children": [
     {
       "bounds": [800, 600],
       "contentsOpaque": true,
       "drawsContent": true,
       "repaintRects": [
         [11, 35, 70, 19],
         [11, 34, 778, 22],
         [11, 11, 51, 19],
-        [11, 11, 51, 19],
         [11, 10, 778, 22]
       ]
     }
   ]
 }