Return MaybeHandle directly instead of converting to Handle first and
then back to MaybeHandle.

Bug: v8:10315
Change-Id: I7d0b67ea3931ad4eba48fc58d934d5722ff70905
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2418402Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70025}