Crash on super call in function with type variable

#2193 causes a crash when calling `super` in function which takes a generic argument (even if the generic argument is unused). Here's the minimum reproducer I've found:

``` py
from typing import TypeVar

T = TypeVar('T', int, str)

class A:
 pass

class B(A):
 def __init__(self, arg):
 # type: (T) -> None
 super(B, self).__init__()
```

@JukkaL @elazarg could you take a look?
