This is a reland of ac79b539

This CL adds a missing BlockPoolsScope to guard a RequestHeapObject
call. This fixes a latend bug that the original land flushed out.

Original change's description:
> [arm64] Refactor constant pool implementation
>
> This refactors the constant pool handling for arm64. The immediate goal
> is to allow 32bit compressed pointers in the pool. The mediate goal is
> to unify the implementation with the arm constant pool, which will be
> done in a follow-up CL.
>
> Bug: v8:8054
> Change-Id: I74db4245e5e1025f2e4de4144090fa4ce25883ab
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1645316
> Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> Reviewed-by: Jakob Gruber <jgruber@chromium.org>
> Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#62209}

TBR=mstarzinger@chromium.org,jgruber@chromium.org,georgia.kouveli@arm.com

Bug: v8:8054
Change-Id: I1e3ab13619a48caad33d77ed8bed86782f9d9674
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1664054Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62237}