E.g. make the setup of the ObjectRef hash table more explicit.

Tbr: jgruber@chromium.org
Bug: v8:7790
Change-Id: I58c03848e7da5c418ff2d6ae1e71b644278f406b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1776089
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63475}