smi size is sill 8 bytes when V8_COMPRESS_POINTERS is undefined.

Bug: v8:7703
Change-Id: I0d1e757e42e8b1e6b10960420135245e24553175
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1508572
Commit-Queue: Junliang Yan <jyan@ca.ibm.com>
Auto-Submit: Junliang Yan <jyan@ca.ibm.com>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60097}