Incorrect type narrowing for TypedDicts using the `S in D` type guard pattern

The narrowed type in the following example is incorrect:

```python
class A(TypedDict):
    a: int

def func(t: A):
    if "b" in t:
        reveal_type(t) # Should be `A`, not `Never`
```

We can't eliminate type `A` based on this check because the TypedDict is not closed.