type information tooltips stopped making sense - 2

followup of #10337

nightly build of Nov 5, 2016
# CASE 1
```typescript
export interface X<A> {
    a: A;
}
export interface Y<B> {
    b: B;
}
export type Z<A, B> = X<A> | Y<B>;

declare function f<A>(): Z<A, number>;
const result = f<string>(); // expected Z<string, number>, actual Z<string>
```
