Lukas Haas, who I remember from “Witness,” has definitely grown up and is now doing more mature roles. "Johns" is his movie, and he’s quite good in it. David Arquette plays John, a character who's about to turn 21 on Christmas Day. He’s trying to spend his birthday at an expensive Los Angeles hotel and makes a living hustling. Haas portrays his friend, a newcomer working the streets. His father is a doctor but disown…