wrong constructor for Blob

[bsr203]

in lib.d.ts, Blob constructor is defined as

declare var Blob: {
    prototype: Blob;
    new(): Blob;
}

It used to be

declare var Blob: {
    prototype: Blob;
    new (blobParts?: any[], options?: BlobPropertyBag): Blob;
}

As per https://developer.mozilla.org/en-US/docs/Web/API/Blob , http://msdn.microsoft.com/en-us/library/windows/apps/hh453178.aspx, it should allow optional parameters.

[RyanCavanaugh]

We should figure out why this happened as part of our lib.d.ts generation rewrite