Tristan Bernays’s adaptation of Mary Shelley’s Frankenstein, directed by Timothy Douglas and playing in repertory with Kate Hamill’s adaptation of Dracula at Classic Stage Company, is a strange hybrid of the ploddingly literal and the vaguely conceptual. Its pleasures lie in listening to Stephanie Berry, who plays both Victor Frankenstein and “the Creature,” recite long passages of beautiful prose. But as a piece of theater, it is a flat, almost somnolent experience, and one that doesn’t seem to say anything new or urgent about the story.