Remove @type_check_only from types with aliases available at runtime

Author: brianschubert

stdlib/asyncio/events.pyi

@@ -600,7 +600,9 @@ class AbstractEventLoop:
     @abstractmethod
     async def shutdown_default_executor(self) -> None: ...
 
-@type_check_only
+# This class does not exist at runtime, but stubtest complains if it's marked as
+# @type_check_only because it has an alias that does exist at runtime. See mypy#19568.
+# @type_check_only
 class _AbstractEventLoopPolicy:
     @abstractmethod
     def get_event_loop(self) -> AbstractEventLoop: ...

stdlib/builtins.pyi

@@ -1340,8 +1340,10 @@ class property:
     def __set__(self, instance: Any, value: Any, /) -> None: ...
     def __delete__(self, instance: Any, /) -> None: ...
 
+# This class does not exist at runtime, but stubtest complains if it's marked as
+# @type_check_only because it has an alias that does exist at runtime. See mypy#19568.
+# @type_check_only
 @final
-@type_check_only
 class _NotImplementedType(Any):
     __call__: None