On Broadway, dance is now more like a shot of espresso or a vintage Instagram filter and less of a storytelling tool, like it used to be. American Dance for the 21st Century, a reincarnation of an earlier effort in the 1970s and '80s, is committed to preserving the type of musical theater dance that is truly part of a show's DNA. For its Joyce debut, the company presents classic dance numbers from shows like "Contact," "A Chorus Line" and "42nd Street."