Invlaid declaration emit with expressions in extend position

``` ts
class C<T, U> {
    x: T;
    y: U;
}

function getClass<T>(c: T) {
    return C;
}

class MyClass extends getClass(2) <string, number> {
}
```

generates:

``` ts
declare class C<T, U> {
    x: T;
    y: U;
}
declare function getClass<T>(c: T): typeof C;
declare class MyClass extends  {
}
```
