GitLab

From flakiness dashboard:
https://test-results.appspot.com/dashboards/flakiness_dashboard.html#testType=webkit_layout_tests&showFlaky=true&builder=chromium.fyi%3AMojo%20Linux

There're more, but adding a few ones that often show flakes (which is
confusing while looking into other flaky issues)

TBR=jam@chromium.org
NOTRY=true

Bug: 729849
Change-Id: I1d862a944f7e1c3a5b792f9783ae56b31ddfdeed
Reviewed-on: https://chromium-review.googlesource.com/746053Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Commit-Queue: Kinuko Yasuda <kinuko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#512787}