Summary:
When the receiver type and return type of an unknown call are the same, propagate taint to both the receiver and the return type.
This does the right thing for common "builder-style" methods that both update and return the receiver.
We already had custom models for a few such methods (e.g., `StringBuilder.append`), but we can remove them now.
Reviewed By: jeremydubreil
Differential Revision: D4490071
fbshipit-source-id: 325ea88
Summary: Generalized the CppTrace into a Clang trace because we don't currently have separate checkers for Obj-C and Cpp. Happy to separate them later if there is a good reason
Reviewed By: akotulski
Differential Revision: D4394952
fbshipit-source-id: e288761
Sam Blackshear