Add unit-test for function and field locations
Add unit-test for function and field locations

Summary: There is a bug that function and field location is not calculated correctly. This diff added unit-test to demonstrate the bug. Notice that `src_range().begin()` is wrong for both function and field. It will be fixed in next diff.

Reviewed By: vitaut

Differential Revision: D35838859

fbshipit-source-id: 70e963802aae54d54c99dd30b0294378c82bbf0d

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