super return value

super1.js

let x;

class A {
  constructor() {
    this.a = true;
    // explictly returns this
    return this;
  }
}

class B extends A {
  constructor() {
    x = super();
  }
}

new B();

assert(x !== void 0);

super2.js

let x;

class A {
  constructor() {
    this.a = true;
    // implicitly returns this?
  }
}

class B extends A {
  constructor() {
    x = super();
  }
}

new B();

assert(x === void 0);