This fixes typing (and type conversions) in the two compilers and adds a
test for executing a memory.size instruction in memory64.

R=manoskouk@chromium.org

Bug: v8:10949
Change-Id: Ic06b224437cb818ad74d0732fc4c8e08c9095231
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2632594
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Manos Koukoutos <manoskouk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72219}