"The meaning of a performance depends most of all on who is in the audience." So says one of the characters in Itamar Moses's scorching new play, The Ally, opening tonight at the Public Theater. So, let's take the playwright at his word and say that if you saw Joshua Harmon's Prayer for the French Republic and were caught up in the whirlwind of passionate socio-political arguments that suffuse that play, you probably…
