Check for scrollable element using jQuery.

scrollable.js

/**
 * Test to get correct scrollable element
 * @return {string}
 * @see  http://www.zachstronaut.com/posts/2009/01/18/jquery-smooth-scroll-bugs.html (updated to use $.scrollTop())
 * @requires jquery 1.7+
 */
getScrollable = function(){
    var result = 'html, body',
        initScrollTop;

    $('html, body').each(function(){
        var $this = $(this);
        
        initScrollTop = $this.scrollTop();
        $this.scrollTop(initScrollTop +1);

        if($this.scrollTop() === initScrollTop + 1){
            result = this.nodeName.toLowerCase();
            $this.scrollTop(initScrollTop);

            return result;
        }
    });

    return result;
};