Bill Nighy made his Broadway debut almost a decade ago in David Hare’s The Vertical Hour. He returns in Skylight, an earlier but better Hare play from 1996, and it’s cause for celebration. In a season marked by alpha stars in beta plays (Bradley Cooper in The Elephant Man; Hugh Jackman in The River), Nighy and co-star Carey Mulligan have a brilliant vehicle worthy of their complementary talents.