Literal type not accepted as key when constructing TypedDict

[JukkaL]

@b0g3r reported an issue with TypedDict keys not being accepted with literal types. Example code from #6262 (comment):

from mypy_extensions import TypedDict
from typing_extensions import Literal, Final


class MyDict(TypedDict):
    field_name: int

d: MyDict
d = {'field_name': 1}  # OK

name_in_var = 'field_name'
d = {name_in_var: 1}  # Correct error

name_in_literal2: Literal['field_name'] = 'field_name'
d = {name_in_literal2: 1}  # Unexpected error

name_in_final: Final = 'field_name'
d = {name_in_final: 1}  # Unexpected error

[b0g3r]

Oh no, I wanted to implement it :(

But thanks anyway!