Check for duplicate methods
Check for duplicate methods

Summary: The same `MethodRef` pointer should never appear twice.

Reviewed By: agampe

Differential Revision: D35031555

fbshipit-source-id: 759da8db8a19cff106a62cd189bb62ebe494ed17

facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex