We want to grow the table entries exponentially, so the entries length
will not reflect the actual size of the table any more. Hence, introduce
another field on {WasmTableObject} to store the actual length.

R=mstarzinger@chromium.org
CC=ecmziegler@chromium.org

Bug: v8:10018
Change-Id: Ie8252f33fddda3ae60dd24bd8db148fd67262226
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1939050
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65200}