Don't include scroll offset in offsetFromLayoutObject for scrolling contents layers.

third_party/WebKit/LayoutTests/compositing/repaint/should-not-clip-composited-overflow-scrolling-layer-expected.txt

 {
   "bounds": [800, 600],
   "children": [
     {
       "bounds": [800, 600],
       "contentsOpaque": true,
       "drawsContent": true,
       "children": [
         {
           "position": [8, 8],
           "bounds": [500, 500],
           "shouldFlattenTransform": false,
           "drawsContent": true,
           "paintInvalidations": [
             {
               "object": "LayoutBlockFlow DIV id='content'",
-              "rect": [-2000, -2000, 5000, 5000],
               "reason": "style change"
             },
             {
               "object": "RootInlineBox",
               "reason": "full"
             }
           ],
           "children": [
             {
               "bounds": [485, 485],
@@ skipping 48 matching lines @@
                 }
               ]
             }
           ]
         }
       ]
     }
   ]
 }