R=titzer@chromium.org

Bug: v8:7965
Change-Id: I1bdd5b3bc8626727c94b95b519a8896384ff990b
Reviewed-on: https://chromium-review.googlesource.com/1148573
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54684}