Ext2.0 Viewport在IE与FireFox运行问题

Viewport在IE下报错 246行错误，而在firefox下通过，items必须renderTo

 

Ext.onReady(function()
       { new Ext.Viewport({
           enableTabScroll:true,
           layout:"fit",
        items:
        [
         { title:"面板",
          html:"ffff",
          bbar: [
            {text:"按钮1"},
            {text:"按钮2"}
             ],
          renderTo:'divId'
         }
        ]

    });
    });