Only the NewSloppyArguments_Generic variant is used, so delete the
unused NewSloppyArguments function and rename the other one to the now
available name.

Change-Id: Ifb90a03bd112f78b4d95f7afc3b299c9634e9acc
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2128051
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66935}