We can move the esize (element size) calculation into the other scope,
since all but 1 instruction share this.

Bug: v8:10933
Change-Id: I43cfef46fdf7e962d54c29949488c2a7c0900334
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2504854Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70860}