Jon M. Chu has made one of the great musicals of our time, a phantasmagorical coming-of-age journey into a land of wide-eyed enchantment, wild dance moves, and colorful, magic bubbles. That movie was called Step Up 3D, and it came out in 2010. Though dismissed by critics at the time, that dance-off sequel feels more like a masterpiece with each passing year, an early demonstration of its director’s ability to spin new worlds through movement and mood. These talents...