Avoid a few handle derefs for this semi-hot startup function.

Change-Id: Id61135d6031905d2bee07cadc1396b144b43df9a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3306428Reviewed-by: Marja Hölttä <marja@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78150}