Annotate TypedDict as _SpecialForm rather than object. (#12985)

* Annotate TypedDict as _SpecialForm rather than object.

Let's see if this works...

* Get typing_extensions.TypedDict as well, try to fix tests.

* Import typing_extensions.TypedDict, delete _SpecialForm.__getitem__.

* Back out deletion of _SpecialForm.__getitem__.

stdlib/@tests/stubtest_allowlists/common.txt

@@ -464,6 +464,7 @@ typing_extensions\.ParamSpec.*
 typing(_extensions)?\.Generic
 typing\.Protocol
 typing(_extensions)?\._TypedDict
+typing(_extensions)?\.TypedDict
 typing._Final
 typing._Final.__init_subclass__
 

stdlib/typing.pyi

@@ -213,8 +213,7 @@ Tuple: _SpecialForm
 Final: _SpecialForm
 
 Literal: _SpecialForm
-# TypedDict is a (non-subscriptable) special form.
-TypedDict: object
+TypedDict: _SpecialForm
 
 if sys.version_info >= (3, 11):
     Self: _SpecialForm

stdlib/typing_extensions.pyi

@@ -58,6 +58,7 @@ from typing import (  # noqa: Y022,Y037,Y038,Y039
     TextIO as TextIO,
     Tuple as Tuple,
     Type as Type,
+    TypedDict as TypedDict,
     Union as Union,
     ValuesView as ValuesView,
     _Alias,
@@ -255,9 +256,6 @@ class _TypedDict(Mapping[str, object], metaclass=abc.ABCMeta):
         # supposedly incompatible definitions of `__ior__` and `__or__`:
         def __ior__(self, value: Self, /) -> Self: ...  # type: ignore[misc]
 
-# TypedDict is a (non-subscriptable) special form.
-TypedDict: object
-
 OrderedDict = _Alias()
 
 def get_type_hints(