Move them to builtins-utils-inl.h instead.

R=titzer@chromium.org

Bug: v8:8015, v8:7965
Change-Id: I692e5871e320896923bed5cc6a2efc609c793446
Reviewed-on: https://chromium-review.googlesource.com/1160845
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54899}