d = $$(".messages-content")[0];
d.__lastST = d.__lastSH = 0;

setInterval(function() {
    if ((d.__lastSH != d.scrollHeight) && (d.__lastST<=d.scrollTop))
    {
        d.scrollTop = d.scrollHeight;
        d.__lastSH = d.scrollHeight;
        d.__lastST = d.scrollTop;
    }
}, 500);