// Broken loop function

function loop() {
    var current = new Date().getTime(),
    delta = current - start;

    if(delta >= delay) {
        fn.call();
        start = new Date().getTime();
    }

    handle.value = requestAnimationFrame(loop);
};

// Fixed loop function

function loop() {
    handle.value = requestAnimationFrame(loop);
    var current = new Date().getTime(),
    delta = current - start;

    if(delta >= delay) {
        fn.call();
        start = new Date().getTime();
    }
};