=== tests/cases/compiler/optionalConstructorArgInSuper.ts ===
class Base {
>Base : Base

    constructor(opt?) { }
>opt : any

    foo(other?) { }
>foo : (other?: any) => void
>other : any
}
class Derived extends Base {
>Derived : Derived
>Base : Base
}
var d = new Derived(); // bug caused an error here, couldn't select overload
>d : Derived
>new Derived() : Derived
>Derived : typeof Derived

var d2: Derived;
>d2 : Derived
>Derived : Derived

d2.foo(); 
>d2.foo() : void
>d2.foo : (other?: any) => void
>d2 : Derived
>foo : (other?: any) => void