Reusing the same {Binary} object (with the same {ArrayBuffer}
underneath) speeds up the limits test with 1M functions by a factor of
11x in an optdebug build.

R=titzer@chromium.org

Change-Id: I36d032d652c66f5b7f5a80399588652d7e3946ec
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1511475Reviewed-by: Ben Titzer <titzer@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60127}