There's no point in having the setup or the toString/valueOf methods in
JavaScript. The full setup can be done during bootstrapping when the
Boolean constructor is created, and the prototype methods don't benefit
from JS + %_ at all.

R=jarin@chromium.org

Review URL: https://codereview.chromium.org/1701273003

Cr-Commit-Position: refs/heads/master@{#34068}