Some roles are practically foolproof. One of them is Billie Dawn, the dumb-blonde girlfriend of a thuggish businessman come to Washington to bribe senators, in Garson Kanin's Born Yesterday. Judy Holliday won a Tony for it in her Broadway debut in 1946; Madeline Kahn took home her own Tony for a 1989 revival. This time, newcomer and first-time Tony contender Nina Arianda gets the plum role, and if she's too much of a ditzy stereotype at the beginning, her performance matures and deepens impressively. Arianda gets the laughs, but also brings out the touching, even inspiring, notes in Garson Kanin's dated but canny comedy.