code: function getExpandoData(ownerDocument) {
      var data = expandoData[ownerDocument[expando]];
      if (!data) {
          data = {};
          expanID++;
          ownerDocument[expando] = expanID;
          expandoData[expanID] = data;
      }
      return data;
    }
docs: Returns the data associated to the given document
  @private
  @param {Document} ownerDocument The document.
  @returns {Object} An object of data.