Revert "Auto-rebaseline for r177431"

LayoutTests/platform/mac/fast/repaint/positioned-document-element-expected.txt

 {
   "bounds": [800, 600],
   "children": [
     {
       "bounds": [800, 600],
       "contentsOpaque": true,
       "drawsContent": true,
       "repaintRects": [
         [108, 116, 425, 18],
         [108, 116, 425, 18],
         [100, 100, 441, 50],
         [8, 16, 784, 18],
         [8, 16, 784, 18],
         [0, 0, 800, 600],
         [0, 0, 800, 50],
+        [0, 0, 800, 50],
         [0, 0, 800, 50]
       ]
     }
   ]
 }