Rooney Mara, the rising star at the heart of “The Girl with the Dragon Tattoo,” advances a few rungs in a shoot for Alluremagazine. Dishing on her dark character’s many risqué scenes, Mara, 26, tells the mag’s January issue: “Nudity is such a huge part of the character in the book, so I never thought twice about it . . . I just showed up and was comfortable.”