You just need to update the 'jquery.combogrid.js' file to the 'plugins' folder and include it on your page.
<script type="text/javascript" src="../../jquery.min.js"></script>
<script type="text/javascript" src="../../jquery.easyui.min.js"></script>
<script type="text/javascript" src="../../plugins/jquery.combogrid.js"></script>