Get object property by typed value

[wclr]

This currenlty doen't work:

let person: { name: string, age: number } = {
  name: 'John', age: 10
} 
type NameOrAge = 'name' | 'age'
let prop: NameOrAge = 'name'

let nameOrAge = person[prop] // `nameOrAge`  would take tape of `string | number`

Is it going to work in near future?

[RyanCavanaugh]

I think this is covered by #6080