Rebecca Rubin Film and Media Reporter “Barbie” towered over the box office for the third consecutive weekend, taking down newcomers “Teenage Mutant Ninja Turtles: Mutant Mayhem” and “Meg 2: The Trench.” Grega Gerwig’s fantasy comedy added a remarkable $52 million in its third weekend of release, a decline of just 43% from its prior frame. “Barbie” has generated $459 million in North America and will imminently cross the $1 billion mark globally. Christopher Nolan’s “Oppenheimer,” too, stayed strong in its third outing with $28.7 million, dropping only 39% from last weekend and bringing domestic ticket sales to $228 million.