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

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

 {
   "layers": [
     {
       "name": "LayoutView #document",
       "bounds": [800, 600],
       "contentsOpaque": true,
       "drawsContent": true
     },
     {
       "name": "LayoutBlockFlow DIV id='intervening'",
@@ skipping 14 matching lines @@
       "name": "Scrolling Layer",
       "position": [1, 1],
       "bounds": [100, 100],
       "shouldFlattenTransform": false
     },
     {
       "name": "Scrolling Contents Layer",
       "bounds": [100, 180]
     },
     {
+      "name": "Decoration Layer",
+      "bounds": [102, 102],
+      "drawsContent": true
+    },
+    {
       "name": "LayoutBlockFlow (positioned) DIV id='fixed'",
       "position": [60, 60],
       "bounds": [80, 80],
       "contentsOpaque": true,
       "drawsContent": true,
       "backgroundColor": "#008000"
     },
     {
       "name": "Squashing Containment Layer",
       "shouldFlattenTransform": false
@@ skipping 18 matching lines @@
       "bounds": [102, 102]
     },
     {
       "name": "Vertical Scrollbar Layer",
       "position": [94, 1],
       "bounds": [7, 100]
     }
   ]
 }