Added a sanity check to the construction of the points-to semantics of a method
Added a sanity check to the construction of the points-to semantics of a method

Summary:
- Check that the definition of a method that is neither abstract nor native always has an associated code component.
- Use a simpler API for the parallel walk over all methods in a scope.

Reviewed By: dariorussi, int3

Differential Revision: D5641888

fbshipit-source-id: c58a460b9659ffefe071d1181d51048a229b9dc2

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