Fix the bug that negative outline-offset is covered up by composited

third_party/WebKit/LayoutTests/platform/linux/paint/invalidation/selection/selection-within-composited-scroller-expected.txt

 {
   "layers": [
     {
       "name": "LayoutView #document",
       "bounds": [800, 600],
       "contentsOpaque": true,
       "drawsContent": true
     },
     {
       "name": "LayoutBlockFlow DIV id='scroller'",
@@ skipping 33 matching lines @@
     {
       "name": "Vertical Scrollbar Layer",
       "position": [185, 0],
       "bounds": [15, 185]
     },
     {
       "name": "Scroll Corner Layer",
       "position": [185, 185],
       "bounds": [15, 15],
       "drawsContent": true
+    },
+    {
+      "name": "Decoration Layer",
+      "bounds": [200, 200],
+      "drawsContent": true
     }
   ],
   "objectPaintInvalidations": [
     {
       "object": "LayoutBlockFlow HTML",
       "reason": "selection"
     },
     {
       "object": "LayoutBlockFlow BODY",
       "reason": "selection"
@@ skipping 10 matching lines @@
       "object": "LayoutText #text",
       "reason": "selection"
     },
     {
       "object": "InlineTextBox 'test'",
       "reason": "selection"
     }
   ]
 }