There are few greater roles in musical theater than that of Fantine, the mother who sacrifices everything for her daughter, Cosette. A factory worker forced to the streets, Fantine’s downfall is what sets much of the plot of “Les Misérables” in motion, as Cosette becomes the adopted daughter of Jean Valjean. It’s no coincidence that early promotion for the film has relied heavily on Hathaway singing “I Dreamed a Dream,” Fantine’s signature song. And as anyone can see or hear, Hathaway delivers.