Summary:
Analyses should handle methods whose code is unknown and methods whose summary is a no-op differently.
Previously, this was done correctly for some kinds of methods (e.g., native methods, which were recognized as unknown), but not for others (interface and abstract methods).
This diff makes sure we correctly treat all three kinds as unknown.
Reviewed By: jeremydubreil
Differential Revision: D4142697
fbshipit-source-id: c88cff3