When implementing Liftoff I realized that these are not tested at all
in our cctests.

R=ahaas@chromium.org

Bug: v8:6600
Change-Id: I9f4da9bb93580f556bc67ebe8b79427373e656ba
Reviewed-on: https://chromium-review.googlesource.com/808385
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49894}