If you are not using them too often, their relationship and meaning is
not totally obvious. Especially that {kTaggedSigned} means "uncompressed
Smi" cannot be inferred from the name.

R=neis@chromium.org

Bug: v8:10021
Change-Id: If684b87ba24da0bbce846d4e35a790c2ee96116b
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1967374Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65457}