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

third_party/WebKit/LayoutTests/compositing/overflow/scrollbar-layer-placement-expected.txt

Index: third_party/WebKit/LayoutTests/compositing/overflow/scrollbar-layer-placement-expected.txt
diff --git a/third_party/WebKit/LayoutTests/compositing/overflow/scrollbar-layer-placement-expected.txt b/third_party/WebKit/LayoutTests/compositing/overflow/scrollbar-layer-placement-expected.txt
index cd12323f9edac4921308e1317421d15045a51d03..9bdb4829ec249020e537cbd79ec08cbc2f2f653e 100644
--- a/third_party/WebKit/LayoutTests/compositing/overflow/scrollbar-layer-placement-expected.txt
+++ b/third_party/WebKit/LayoutTests/compositing/overflow/scrollbar-layer-placement-expected.txt
@@ -42,6 +42,11 @@
       "bounds": [7, 160]
     },
     {
+      "name": "Decoration Layer",
+      "bounds": [278, 218],
+      "drawsContent": true
+    },
+    {
       "name": "LayoutBlockFlow (positioned) DIV class='outer B'",
       "position": [355, 6],
       "bounds": [340, 282],
@@ -67,6 +72,11 @@
       "drawsContent": true
     },
     {
+      "name": "Decoration Layer",
+      "bounds": [278, 218],
+      "drawsContent": true
+    },
+    {
       "name": "LayoutBlockFlow (relative positioned) DIV class='content'",
       "position": [73, 73],
       "bounds": [196, 212],
@@ -116,6 +126,11 @@
       "drawsContent": true
     },
     {
+      "name": "Decoration Layer",
+      "bounds": [278, 218],
+      "drawsContent": true
+    },
+    {
       "name": "LayoutBlockFlow (relative positioned) DIV class='content'",
       "position": [72, 72],
       "bounds": [196, 212],
@@ -181,6 +196,11 @@
       "drawsContent": true
     },
     {
+      "name": "Decoration Layer",
+      "bounds": [278, 218],
+      "drawsContent": true
+    },
+    {
       "name": "LayoutBlockFlow (relative positioned) DIV class='content'",
       "position": [72, 72],
       "bounds": [196, 212],