R=titzer@chromium.org

Bug: v8:7581
Change-Id: I3a1fcffd3429907bcf9f92a904ab30568e6d4d07
Reviewed-on: https://chromium-review.googlesource.com/998914
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52501}