The {parameter_count} is always equal to {kParameterCount}, so just use
{kParameterCount} directly.

R=ishell@chromium.org

Bug: v8:7754
Change-Id: I136387b5f2da3af10bb36215f947ff0e0d872928
Reviewed-on: https://chromium-review.googlesource.com/1109820Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53916}