Inside, the buzzing throng might have surprised me, except for two things. This was my second show of the day, and the first — a matinee of Manual Cinema’s “The 4th Witch” — had filled its theater. Also, this “A Doll’s House,” a variation on Ibsen’s classic by the French-Norwegian company Plexus Polaire, is the production that lured me to Chicago, where I’d first seen its work in 2017. “A Doll’s House” was an American premiere, and only three performances were planned. Of course devotees were undeterred.