Indentation not made after a function parameter list with a type hint

## Actual behavior

![example](https://user-images.githubusercontent.com/54418/39159360-f2d51078-4719-11e8-86d5-0eb32cc1e2be.gif)

## Expected  behavior

The cursor to indent after hitting Enter.

## Steps to reproduce:
```python
def foo(x: int):
```