If module bytes end in a prefix like 0xfc (numeric prefix), we read out
of bounds (pc + 1). So, if validate flag is set, check the length.

Bug: chromium:1073553
Change-Id: Ia9771419d01f2315723d19dd96630172b5a7a1f5
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2161404Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67370}