noImplicitReturns compile error for void functions as of 1.8.0-dev.20151126

As of `1.8.0-dev.20151126` the following now generates a compile error when `noImplicitReturns` is specified in `tsconfig.json`:

``` typescript
let x = () => { console.log("Test"); }
```

```
Not all code paths return a value.
```

even though the type of `x` is `() => void`

This feels like a bug to me...
