R=titzer@chromium.org

Bug: v8:6600
Change-Id: I2adb5a74cfdc6ec7e229f1ca1bd31d8209156617
Reviewed-on: https://chromium-review.googlesource.com/1167519Reviewed-by: Ben Titzer <titzer@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55002}