R=titzer@chromium.org

Bug: v8:7581
Change-Id: I51c585aafa71cbc20565974929cba8327d7f8427
Reviewed-on: https://chromium-review.googlesource.com/973305
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52133}