... in favor of [Full]MaybeObjectSlot and finally make deserializer
pointer compression friendly.

Bug: v8:8794
Change-Id: I23e5b119ccfe7d0c12c15a857978d89813e0522f
Reviewed-on: https://chromium-review.googlesource.com/c/1460460
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59472}