The uint32_t type can easily be confused with the memory offsets that
are currently 32 bit and will become 64 bit with the memory64 proposal.
Since the offsets into the instance are always small anyway, the type of
the integer does not really matter, and we should stick to the default
'int'.

R=manoskouk@chromium.org

Bug: v8:10949
Change-Id: I742334483bbc80c4cc03f40f046b5d2d3b17d1d8
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2489691
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Manos Koukoutos <manoskouk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70712}