Mark fast/scroll-snap/snaps-after-scrollbar-scrolling.html as flaky/slow

Bug: 864887
Change-Id: I9210134ed670cd46026cd6f9d83a6336460ea140
Tbr: sunyunjia@chromium.org
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/1141453
Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Commit-Queue: Yutaka Hirano <yhirano@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575945}
2 files changed