Even though this is not spec'ed yet, it's good to have an implementation
so that we can use clusterfuzz on it.

R=binji@chromium.org

Bug: v8:7581
Change-Id: I323625322e5240dc6ac224dce8a1f1f7f6070758
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1695478Reviewed-by: Ben Smith <binji@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62656}