... to support creation of fillers in external code space.

Bug: v8:11880
Change-Id: I47b352b8b44733c529b6b0cb2b39cf676ce83923
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3208813
Auto-Submit: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77271}