Improve None as predicate for Python 2 ifilter (#8191)

Author: david-askari

stdlib/@python2/itertools.pyi

@@ -22,7 +22,10 @@ class chain(Iterator[_T], Generic[_T]):
 
 def compress(data: Iterable[_T], selectors: Iterable[Any]) -> Iterator[_T]: ...
 def dropwhile(predicate: Callable[[_T], Any], iterable: Iterable[_T]) -> Iterator[_T]: ...
-def ifilter(predicate: Callable[[_T], Any] | None, iterable: Iterable[_T]) -> Iterator[_T]: ...
+@overload
+def ifilter(predicate: None, iterable: Iterable[_T | None]) -> Iterator[_T]: ...
+@overload
+def ifilter(predicate: Callable[[_T], Any], iterable: Iterable[_T]) -> Iterator[_T]: ...
 def ifilterfalse(predicate: Callable[[_T], Any] | None, iterable: Iterable[_T]) -> Iterator[_T]: ...
 @overload
 def groupby(iterable: Iterable[_T], key: None = ...) -> Iterator[tuple[_T, Iterator[_T]]]: ...