This allows us to use them in constexpr contexts, just as DCHECK.
There were some "constexpr" keywords missing, and we cannot have
explicit template instantiations for constexpr.

R=jkummerow@chromium.org

Bug: v8:9810
Change-Id: Iba7c6ed4a16ea5077324880f59f7f0e17d1757a4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1910956Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64921}