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

third_party/WebKit/LayoutTests/paint/invalidation/composited-overflow-with-negative-offset-outline.html

Index: third_party/WebKit/LayoutTests/paint/invalidation/composited-overflow-with-negative-offset-outline.html
diff --git a/third_party/WebKit/LayoutTests/paint/invalidation/composited-overflow-with-local-background.html b/third_party/WebKit/LayoutTests/paint/invalidation/composited-overflow-with-negative-offset-outline.html
similarity index 59%
copy from third_party/WebKit/LayoutTests/paint/invalidation/composited-overflow-with-local-background.html
copy to third_party/WebKit/LayoutTests/paint/invalidation/composited-overflow-with-negative-offset-outline.html
index bd687e8c6f03922cc20b2847c9c69731ad6b3618..c8637afd620fcf7000ba3c48f0eb1392fc82e21a 100644
--- a/third_party/WebKit/LayoutTests/paint/invalidation/composited-overflow-with-local-background.html
+++ b/third_party/WebKit/LayoutTests/paint/invalidation/composited-overflow-with-negative-offset-outline.html
@@ -2,25 +2,26 @@
 <script src="resources/text-based-repaint.js"></script>
 <script>
 function repaintTest() {
-    scroller.style.background = 'green local';
+    scroller.style.outline = '1px solid green';
 }
 onload = runRepaintAndPixelTest;
 </script>
 <style>
 #scroller {
-    background: red local;
     overflow: scroll;
     width: 200px;
     height: 200px;
     will-change: transform;
+    outline: 1px solid blue;

[flackr, 2016/10/25 21:26:30]

nit: it may be good to start the outline red so that if it fails to update it is
obvious that it is the wrong color.

[yigu, 2016/10/27 20:21:26]

That makes more sense.

+    outline-offset: -4px;
 }
 
 .spacer {
     height: 300px;
 }
 </style>
-<!-- #scroller has a locally attached background which will be painted into the
-    scrolling contents layer. When the color changes it should repaint. -->
+<!-- #scroller has a negative offset outline which should not be covered up by
+    the scrollbar. When the color changes it should repaint. -->
 <div id="scroller">
     <div class="spacer"></div>
 </div>