Use the provided non-nil keyPath.
Use the provided non-nil keyPath.

Reviewers: O2 Material Motion, #material_motion, O4 Material Apple platform reviewers, chuga

Reviewed By: O4 Material Apple platform reviewers, chuga

Tags: #material_motion

Differential Revision: http://codereview.cc/D2406

material-motion/material-motion-swift,material-motion/material-motion-swift