code: function(el, attributes, duration,  method) {
          if (el) { // dont break existing subclasses not using YAHOO.extend
              Scroll.superclass.constructor.call(this, el, attributes, duration, method);
          }
      }
docs: Anim subclass for scrolling elements to a position defined by the "scroll"
  member of "attributes".  All "scroll" members are arrays with x, y scroll positions.
  <p>Usage: <code>var myAnim = new YAHOO.util.Scroll(el, { scroll: { to: [0, 800] } }, 1, YAHOO.util.Easing.easeOut);</code></p>
  @class Scroll
  @namespace YAHOO.util
  @requires YAHOO.util.Anim
  @requires YAHOO.util.AnimMgr
  @requires YAHOO.util.Easing
  @requires YAHOO.util.Bezier
  @requires YAHOO.util.Dom
  @requires YAHOO.util.Event
  @requires YAHOO.util.CustomEvent
  @extends YAHOO.util.ColorAnim
  @constructor
  @param {String or HTMLElement} el Reference to the element that will be animated
  @param {Object} attributes The attribute(s) to be animated.
  Each attribute is an object with at minimum a "to" or "by" member defined.
  Additional optional members are "from" (defaults to current value), "units" (defaults to "px").
  All attribute names use camelCase.
  @param {Number} duration (optional, defaults to 1 second) Length of animation (frames or seconds), defaults to time-based
  @param {Function} method (optional, defaults to YAHOO.util.Easing.easeNone) Computes the values that are applied to the attributes per frame (generally a YAHOO.util.Easing method)