Trim trailing whitespace in d.ts output

[jednano]

Here's a scenario in which trailing whitespace is not trimmed in d.ts output, specifically when adding jsdoc-style comments above each arg with line breaks in-between:

export class Point {
    constructor(
        /**
         * The x coordinate.
         */
        public x: number,
        /**
         * The y coordinate.
         */
        public y: number
    ) {

    }
}

The generated output has spaces after each argument's comma that has another argument after it. In this case, only the x arg has the space after the comma:

define(["require", "exports"], function (require, exports) {
    var Point = (function () {
        function Point(
            /**
             * The x coordinate.
             */
            x, <-- trailing whitespace!
            /**
             * The y coordinate.
             */
            y) {
            this.x = x;
            this.y = y;
        }
        return Point;
    })();
    exports.Point = Point;
});

See the result on the TypeScript Playground.

[mhegazy]

A PR would be appreciated.

[DanielRosenwasser]

@yuit and I spent a good bit of time looking into alternative approaches, and while we got something that works decently, the gain seems relatively marginal compared to the hoops we had to jump through.

I think that overall this is easily amended by a pretty-printer or minifier.