Report error which Flow does not report

This use case is where, in C/C++, a forward declaration would be needed.

`A.js`:
```js
// @flow

import B from './B';

export default class A {
a() { return new B(this); }
}
```

`B.js`:
```js
// @flow

import type A from './A';

export default class B {
a: A;

constructor(a: A) {
this.a = a;
}
}
```

Flow says `No errors!` but `flowtype-errors/show-errors` reports the following in `A.js`:
```
6:23 A: This type is incompatible with the expected param type of A. See ./B.js:8
```