FitOutside = function (target, source) {
    var ratio = GetAspectRatio(target);

    if (ratio > GetAspectRatio(source)) {
        //  Wider than Tall
        target.setSize(source.height * ratio, source.height);
    }
    else {
        //  Taller than Wide
        target.setSize(source.width, source.width / ratio);
    }

    return target.setPosition(
        source.centerX - target.width / 2,
        source.centerY - target.height / 2
    );
}
Adjusts the target rectangle, changing its width, height and position,
so that it fully covers the area of the source rectangle, while maintaining its original
aspect ratio.

Unlike the `FitInside` function, the target rectangle may extend further out than the source.

@function Phaser.Geom.Rectangle.FitOutside
@since 3.0.0

@generic {Phaser.Geom.Rectangle} O - [target,$return]

@param {Phaser.Geom.Rectangle} target - The target rectangle to adjust.
@param {Phaser.Geom.Rectangle} source - The source rectangle to envlope the target in.

@return {Phaser.Geom.Rectangle} The modified target rectangle instance.