fix typo in type mapper matchprop case
fix typo in type mapper matchprop case

Summary: This is obviously wrong, so I fixed it

Reviewed By: samwgoldman

Differential Revision: D23408032

fbshipit-source-id: 1f5bdac28a2e2e61805ab673e5c81a01e37e00ab

facebook/flow,facebook/flow,facebook/flow,mroch/flow,mroch/flow,facebook/flow,mroch/flow,mroch/flow,facebook/flow,mroch/flow,mroch/flow,facebook/flow,mroch/flow,facebook/flow