The Number.parseInt (and therefore the parseInt function on the global
object) are often used instead of Math.floor or just plain int32
truncation, and we can easily recognize those cases and provide a fast
path in TurboFan.

R=jarin@chromium.org

Review-Url: https://codereview.chromium.org/2125583002
Cr-Commit-Position: refs/heads/master@{#37518}