This ports ObjectStartBitmap from Blink.

Bug: chromium:1056170
Change-Id: Ib959d9ac1c5e1e34ffa6418f77956e993c570ffc
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2181331
Commit-Queue: Anton Bikineev <bikineev@chromium.org>
Reviewed-by: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67735}