This code must move into builtins since --jitless disallows executable
memory allocation at runtime. Removing CPU-dependent code will make that
step easier.

The hope is that processors have gotten better in the last couple of
years and this code is unnecessary by now.

Bug: v8:8675
Change-Id: I1f2f104befc5f65f1dd69e9643cc51290d2465b8
Reviewed-on: https://chromium-review.googlesource.com/c/1407061Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58770}