The future of the Art Institute of Chicago is in plastics. That is, plastics mogul Stefan Edlis and his wife, Gael Neeson, who last April donated 44 works of pop art valued at $400 million—the biggest gift in the museum’s history. While a $35 million cash gift from the late Dorothy Braude Edinburg made news recently, that money doesn’t buy even one marquee Warhol. The Edlis-Neeson collection boasts 10.