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

third_party/WebKit/LayoutTests/compositing/overflow/clear-scroll-parent-expected.txt

 {
   "layers": [
     {
       "name": "LayoutView #document",
       "bounds": [800, 600],
       "contentsOpaque": true,
       "drawsContent": true
     },
     {
       "name": "LayoutBlockFlow DIV class='container'",
@@ skipping 23 matching lines @@
       "position": [289, 4],
       "bounds": [15, 185]
     },
     {
       "name": "Scroll Corner Layer",
       "position": [289, 189],
       "bounds": [15, 15],
       "drawsContent": true
     },
     {
+      "name": "Decoration Layer",
+      "bounds": [308, 208],
+      "drawsContent": true
+    },
+    {
       "name": "LayoutBlockFlow (positioned) DIV id='fixed'",
       "position": [50, 200],
       "bounds": [200, 200],
       "contentsOpaque": true,
       "drawsContent": true,
       "backgroundColor": "#008000"
     },
     {
       "name": "Ancestor Clipping Layer",
       "position": [12, 12],
@@ skipping 22 matching lines @@
     },
     {
       "name": "Squashing Layer (first squashed layer: LayoutBlockFlow (relative positioned) DIV class='box')",
       "position": [22, 212],
       "bounds": [100, 320],
       "drawsContent": true
     }
   ]
 }