GitLab

Looks like it passes, it just needs a little extra time. Imported from
web-platform-tests so addressing the slowness may take a while to
improve the test.

BUG=521857
TBR=ojan@chromium.org

Review URL: https://codereview.chromium.org/1299223005 .

git-svn-id: svn://svn.chromium.org/blink/trunk@200929 bbb929c8-8fbe-4397-9dbb-9b2b20218538