How to handle warnings for proprietary/custom properties of built-in objects in TypeScript

1)
You can reinterpret navigator prop.

(<any>navigator).id.request();

2)
You can declare id prop youself

mycompany.lib.d.ts

interface Navigator {
  id: any
}

app.ts

navigator.id.request();

see this video http://channel9.msdn.com/posts/Anders-Hejlsberg-Introducing-TypeScript/ There Anders tell as jQuery.UI add new methods to jQuery (see 46 min)