A 12-year-old Australian boy died after a brutal shark attack in Sydney Harbor, his family confirmed Saturday.  Nico Antic had been fighting for his life since Jan. 18, when he was attacked while swimming at a popular cliff-jumping spot known as Jump Rock near Shark Beach in the eastern Sydney suburb of Vaucluse.  His family announced Saturday that he had died. “We are heartbroken to share that our son, Nico, has passed away,” Nico’s parents, Lorena and Juan, said in a statement. “Nico was a