The regression is already fixed. This just adds a regression test to
ensure it will never be reintroduced.

R=ahaas@chromium.org
BUG=chromium:729991

Change-Id: I5cf960cc756cbb7723041bc06a78d6a14c66e241
Reviewed-on: https://chromium-review.googlesource.com/525538Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45739}