gents doesn't convert function type annotations with the new token correctly

[stringham]

/** @type{function(new:A,number,string)} */
let b = A;

gets converted into

let b:(p1: number, p2: string) => any = A;

but should be converted to

let b: new (p1: number, p2: string) => A = A;

To work around this, we made the gents keep the comments that had function(new: in them and fixed the issues afterwards. If you're interested in a PR like this, let me know.