Allow subclass constructors without super() call #7285

TypeScript Version:

1.8.0

Code

Custom element classes often have constructors that just return document.createElement(), since HTMLElement doesn't have a callable constructor, but this generates an error in TypeScript:

class MyElement extends HTMLElement {
  constructor() {
    return document.createElement('my-element');
  }
}

In general, it is completely valid ES2015 to not call super(), as long as you don't access this.