Add helper to check if method is a native method
Add helper to check if method is a native method

Reviewed By: int3

Differential Revision: D15442258

fbshipit-source-id: c2341d8850e304cdf3e447ab518235cf8ca4b022

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