Revert of Clip scrollbars to box bounds when they don't fit.

third_party/WebKit/LayoutTests/compositing/overflow/scroll-parent-with-non-stacking-context-composited-ancestor-expected.txt

 {
   "bounds": [800, 600],
   "children": [
     {
       "bounds": [800, 600],
       "contentsOpaque": true,
       "drawsContent": true,
       "children": [
         {
           "position": [98, 90],
@@ skipping 40 matching lines @@
             },
             {
               "position": [103, 139],
               "bounds": [60, 128],
               "drawsContent": true
             }
           ]
         },
         {
           "position": [98, 90],
-          "bounds": [102, 102],
           "children": [
             {
               "position": [94, 1],
               "bounds": [7, 100]
             }
           ]
         }
       ]
     }
   ]
 }