Remove Overlay Scrollbar if not scrollable along the axis

LayoutTests/platform/linux/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 47 matching lines @@
               "position": [103, 139],
               "bounds": [60, 128],
               "drawsContent": true
             }
           ]
         },
         {
           "position": [98, 90],
           "children": [
             {
-              "position": [1, 94],
-              "bounds": [93, 7]
-            },
-            {
               "position": [94, 1],
-              "bounds": [7, 93]
-            },
-            {
-              "position": [94, 94],
-              "bounds": [7, 7],
+              "bounds": [7, 100],
               "drawsContent": true
             }
           ]
         }
       ]
     }
   ]
 }