This refactors the innards of HandleBase and IdentityMap
to use Address instead of Object*, as part of the quest
to get rid of Object* entirely.

Bug: v8:3770
Change-Id: I82bd9547ef0d208b1e42636792e21c9064af4cea
Reviewed-on: https://chromium-review.googlesource.com/c/1285396
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56797}