Memory access offsets are unsigned. Sign-extending them incorrectly
treats some large offsets as negative numbers and results in
out-of-bounds errors for in-bounds accesses.

This caused a failure in test/mjsunit/wasm/huge-memory.js for arm64, and
for x64 with --nowasm_trap_handler.

Change-Id: If58fead1d115f16ba4a6c3680252111fba6843d1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2002821
Commit-Queue: Georgia Kouveli <georgia.kouveli@arm.com>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65838}