This CL applies the equivalent of the Object -> ObjectPtr
transformation to MaybeObject and HeapObjectReference. We
need no renaming in this case because we can just migrate
them both in one go.

Bug: v8:3770
Change-Id: Ie1259c3e8c556eff00f8bcf534d7270ca9fe00e1
Reviewed-on: https://chromium-review.googlesource.com/c/1298386
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57010}