The constructor for an ES6 Set takes an optional iterable parameter (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set) but the declaration in lib.d.ts doesn't include it

declare var Set: {
    new <T>(): Set<T>;
}

So I'm getting a Typescript error if I try to do something like new Set([1,2,3]).

On a somewhat related note I'm using the 1.5 Beta version of typescript which supports a lot of ES6 features but it still relies on the browser to support Sets. Are there plans polyfill Sets in Typescript?