We will need more Smi loading for exception handling, hence refactor the
existing code to reduce duplication and increase readability.

R=ahaas@chromium.org

Bug: v8:11453
Change-Id: If12ddf607e3aeb7ce0448d977d0d450127caf1d5
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2692818Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72761}