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

third_party/WebKit/LayoutTests/fast/repaint/overflow-move-after-scroll-expected.txt

 {
   "bounds": [800, 600],
   "children": [
     {
       "bounds": [800, 600],
       "contentsOpaque": true,
       "drawsContent": true,
       "children": [
         {
           "position": [10, 60],
           "bounds": [700, 400],
           "shouldFlattenTransform": false,
           "drawsContent": true,
           "paintInvalidations": [
             {
               "object": "LayoutBlockFlow (positioned) DIV id='block'",
-              "rect": [300, 100, 120, 50],
-              "reason": "bounds change"
-            },
-            {
-              "object": "LayoutBlockFlow (positioned) DIV id='block'",
-              "rect": [50, 100, 120, 50],
               "reason": "bounds change"
             }
           ],
           "children": [
             {
               "bounds": [685, 385],
               "shouldFlattenTransform": false,
               "children": [
                 {
                   "bounds": [685, 600],
@@ skipping 38 matching lines @@
                 }
               ]
             }
           ]
         }
       ]
     }
   ]
 }