Emma Watson and fellow stars of the angsty teen tale “The Perks of Being a Wallflower” bonded like high schoolers while celebrating their Nylon magazine cover Saturday. Watson, Ezra Miller and Logan Lerman were at Meatpacking District restaurant Catch, “rocking snow hats with kitty ears, walking around the tables and snapping photos.” The props came from Forever 21 and Sanrio’s Hello Kitty Forever gift bags. Miller said he’d use a Hello Kitty blanket “on his early flight to LA, to help him sleep,” a spy said.