Set scrollbar enabled state for overflow:auto.

third_party/WebKit/LayoutTests/paint/invalidation/flexbox/scrollbars-changed-expected.txt

Index: third_party/WebKit/LayoutTests/paint/invalidation/flexbox/scrollbars-changed-expected.txt
diff --git a/third_party/WebKit/LayoutTests/paint/invalidation/flexbox/scrollbars-changed-expected.txt b/third_party/WebKit/LayoutTests/paint/invalidation/flexbox/scrollbars-changed-expected.txt
index 5285836dd84cc9ac153d62d14d5de60a240c4f7b..86822d82c28afa965293ba6e5ae7d9c143a81019 100644
--- a/third_party/WebKit/LayoutTests/paint/invalidation/flexbox/scrollbars-changed-expected.txt
+++ b/third_party/WebKit/LayoutTests/paint/invalidation/flexbox/scrollbars-changed-expected.txt
@@ -57,6 +57,16 @@
         },
         {
           "object": "Vertical Scrollbar Layer",
+          "rect": [0, 0, 15, 210],
+          "reason": "full"

[bokan, 2016/11/17 17:04:45]

The extra invalidations come from changing the enabled state on an overflow:auto
scrollbar, which didn't happen before. This shouldn't matter though because if
we've changed the enabled state, the scrollbar is about to be removed which will
cause an invalidation anyway.

[skobes, 2016/11/17 21:18:23]

Acknowledged.

+        },
+        {
+          "object": "Vertical Scrollbar Layer",
+          "rect": [0, 0, 15, 100],
+          "reason": "full"
+        },
+        {
+          "object": "Vertical Scrollbar Layer",
           "rect": [0, 0, 15, 100],
           "reason": "full"
         },