TypedDict narrowing regression with enum literal

[JukkaL]

The following example started generating a false positive after #9097:

from typing import TypedDict, Literal, Union
from enum import Enum

class E(Enum):
    FOO = "a"
    BAR = "b"

class Foo(TypedDict):
    tag: Literal[E.FOO]
    x: int

class Bar(TypedDict):
    tag: Literal[E.BAR]
    y: int

def f(d: Union[Foo, Bar]) -> None:
    assert d['tag'] == E.FOO
    d['x']  # TypedDict "Bar" has no key "x"

Type narrowing should work and there should be no error reported.