Unity 3D Javascript appear color fade coroutine version

var colorStart : Color = Color.red;
var colorEnd : Color = Color.green;
var animationDuration : float = 1.0;
private var startTime : float;
private var endTime : float;

function Appear () {

    renderer.enabled = true;

    startTime = Time.time;
    endTime = startTime + animationDuration;

    while (Time.time < endTime) {

        var i = Mathf.InverseLerp(startTime, endTime, Time.time);
        renderer.material.color = Color.Lerp (colorStart, colorEnd, i);
        finished = (Time.time > endTime);
        yield null;
    }

    renderer.enabled = false;

}