Read-only heap objects are immutable and immovable. It is safe to access
these objects directly from the heap. Not having to serialize them
reduces the time we spend on main thread especially for TurboProp.

Bug: v8:9684
Change-Id: Ibabb7076af50c9007d2a8ed57fe257406958fb6a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1955596Reviewed-by: Michael Stanton <mvstanton@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Commit-Queue: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65490}