first = function (canvasType)
    {
        if (canvasType === undefined) { canvasType = CONST.CANVAS; }

        if (canvasType === CONST.WEBGL)
        {
            return null;
        }

        for (var i = 0; i < pool.length; i++)
        {
            var container = pool[i];

            if (!container.parent && container.type === canvasType)
            {
                return container;
            }
        }

        return null;
    }
Gets the first free canvas index from the pool.

@function Phaser.Display.Canvas.CanvasPool.first
@since 3.0.0

@param {number} [canvasType=Phaser.CANVAS] - The type of the Canvas. Either `Phaser.CANVAS` or `Phaser.WEBGL`.

@return {HTMLCanvasElement} The first free canvas, or `null` if a WebGL canvas was requested or if the pool doesn't have free canvases.