The following instructions are affected: memory.init, data.drop,
table.init, table.drop. A segment index should be decoded as an unsigned
number, but these instructions were decoding as signed. This works
properly up to 63, but fails at 64 (which is decoded as -64 =
4294967232).

Bug: v8:10151
Change-Id: I742b74cf0bcadf2ff2f606beb65b7bae3e816530
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2015960Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Ben Smith <binji@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65957}