Elements is already set by CSA::AllocateJSArray.

Bug: v8:7871
Cq-Include-Trybots: luci.v8.try:v8_linux_noi18n_rel_ng
Change-Id: I89b87f9f33eca4a92216f248606fb746f0de5412
Reviewed-on: https://chromium-review.googlesource.com/1168487
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55004}