code: function(fnSort, desc, field) {
          return this._records.sort(function(a, b) {return fnSort(a, b, desc, field);});
      }
docs: Sorts all Records by given function. Records keep their unique IDs but will
  have new RecordSet position indexes.
  
  @method sortRecords
  @param fnSort {Function} Reference to a sort function.
  @param desc {Boolean} True if sort direction is descending, false if sort
  direction is ascending.
  @param field {String} The field to sort by, from sortOptions.field
  @return {YAHOO.widget.Record[]} Sorted array of Records.