R=clemensh@chromium.org

Bug: v8:6756
Change-Id: I3b25b89f3ead5c856be5c7ba3c7c236e595ce8de
Reviewed-on: https://chromium-review.googlesource.com/695524
Commit-Queue: Ben Titzer <titzer@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48333}