Mark 'fast/events/middleClickAutoscroll-event-fired.html' as flaky.

TBR=wjmaclean@chromium.org

Bug: 891155
Change-Id: I149449fe0f847f23edc5b0565c76c5ace3c79afd
Reviewed-on: https://chromium-review.googlesource.com/c/1281049
Reviewed-by: Chan Li <chanli@chromium.org>
Commit-Queue: Chan Li <chanli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#599687}
1 file changed