Fix bug in typeshed:get_pytd_paths and delete internal dataclasses stub.

I noticed this while grepping for stray Python 2.7 references. The incorrect
paths here were why the opensource tests were complaining about dataclasses. We
should actually be able to delete dataclasses.pytd, since dataclasses is in the
stdlib in 3.7.

I still don't know why test_dataclasses passes in 3.6, but it was passing
before we opensourced dataclasses.pytd a few days ago and is still passing now
that I've deleted dataclasses.pytd, so ¯\_(ツ)_/¯

PiperOrigin-RevId: 392537915

pytype/pytd/typeshed.py

@@ -262,7 +262,7 @@ def get_typeshed_paths(self):
   def get_pytd_paths(self):
     """Gets the paths to pytype's version-specific pytd files."""
     return [pytype_source_utils.get_full_path(d)
-            for d in ("stubs/builtins/3", "stubs/stdlib/3")]
+            for d in ("stubs/builtins", "stubs/stdlib")]
 
   def _list_modules(self, path, python_version):
     """Lists modules for _get_module_names_in_path."""

pytype/pytd/typeshed_test.py

@@ -63,7 +63,7 @@ def test_get_pytd_paths(self):
       # reads from TYPESHED_HOME.
 
       paths = {p.rsplit("pytype/", 1)[-1] for p in self.ts.get_pytd_paths()}
-      self.assertSetEqual(paths, {"stubs/builtins/3", "stubs/stdlib/3"})
+      self.assertSetEqual(paths, {"stubs/builtins", "stubs/stdlib"})
     finally:
       os.environ = old_env
 

pytype/stubs/CMakeLists.txt

@@ -16,7 +16,6 @@ filegroup(
     builtins/attr/setters.pytd
     builtins/attr/validators.pytd
     builtins/builtins.pytd
-    builtins/dataclasses.pytd
     builtins/mypy_extensions.pytd
     builtins/numpy/__init__.pytd
     builtins/protocols.pytd