as part of the ongoing quest to get rid of Object*/Object** entirely.
Design overview: https://goo.gl/Ph4CGz

Bug: v8:3770
Change-Id: Ie79a461a61203ea5a6efcd7b2a31bff1834169dd
Reviewed-on: https://chromium-review.googlesource.com/c/1316607
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57306}