Jason Kidd’s son T.J. may have said it best. “He’s still got it,” the younger Kidd said outside the Knicks locker room Saturday. A month ago, Jason turned 40. A month from now, his team might still be playing in the postseason in part because of him. The future Hall of Famer remains a wonder, as was his Knicks playoff debut at the Garden, Logging 35 minutes — only Carmelo Anthony and Raymond Felton played more for the Knicks — Kidd delivered eight points, five rebounds, three assists and three steals in the 85-78, playoff-opening, victory over the Celtics. All three of Kidd’s thefts came in the fourth quarter as the Knicks held the Celtics to just eight points in the final period. “J-Kidd, he was just spectacular,” Anthony said. Kidd’s most dazzling steal came with 4:48 to play. As he was in the process of taking the ball from Boston’s Jeff Green, Kidd dove on the floor to successfully secure possession. That led to Felton being fouled five seconds later, and he sunk one of two free throws to put the Knicks up 79-74. “Champion’s heart,” said Tyson Chandler, a championship teammate of Kidd’s with the Mavericks. “You’ve got a guy 40 years old stripping the ball and then diving on the floor, that’s key.”