Infer type arguments from 'super()' calls

[DanielRosenwasser]

interface Component {
  whatever: number;
}

type ComponentConstructor = new <T = {}>(extra: T) => Component & T;
declare const Component: ComponentConstructor;

class ReallyOldComponent extends Component {
  constructor() {
    super({ name: "Methuselah", age: 969 });
  }
  blah() {
    this.whatever;
    this.age;
  }
}

Ideally this would produce no errors; in fact, ideally I wouldn't need to specify any type parameter defaults on ComponentConstructor's signature. However, instead, T is inferred as {} and in blah it is an error to access this.age.