R=ahaas@chromium.org

Bug: v8:7508, v8:6600
Change-Id: I9eb04171eb489383bb746e2d04c6ffff304b7918
Reviewed-on: https://chromium-review.googlesource.com/942821Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51652}