code: function(doc) {
              doc = doc || document;
              return Math.max(doc[DOCUMENT_ELEMENT].scrollTop, doc.body.scrollTop);
          }
docs: Returns the top scroll value of the document
  @method getDocumentScrollTop
  @param {HTMLDocument} document (optional) The document to get the scroll value of
  @return {Int}  The amount that the document is scrolled to the top