Bug for this-type in literal object type

This code causes an error:

```
type X<A> = {x: A}

interface Foo {
    // works
    a(): X<this>
    // does not work
    b(): {x: this}
}
```

Output:

```
foo.ts(7,11): error TS2526: A 'this' type is available only in a non-static member of a class or interface.
```

It errors if the object type is defined inline, but works for a typedef.
