Opening this weekend: Birds of Prey (and the Fantabulous Emancipation of One Harley Quinn)—Armed with a broad Gotham accent, Margot Robbie is endearingly crazy-eyed, manic and girlishly bouncy as Harley Quinn, the Joker’s jilted, heartsick ex, in this newest DC free-for-all. When she’s not dodging old enemies who bear her any number of murderous grudges, she’s helping super-anti-heroine team Birds of Prey defend an adolescent (Ella Jay Basco) from a scuzzy, sadistic gangster whose alter...