cannot call 'open' method 关于DWR Chrome 调用的解决方法

dwr包是2.10，chrome是最新版本 26.0.1410.64 m，

会提示cannot call 'open' method，
解压出\org\directwebremoting\engine.js的文件
debug进去发现如下的open方法这时候是 underfined

try {  
          batch.req.open(httpMethod, request.url, batch.async);  
          try {  
            for (var prop in batch.headers) {  
              var value = batch.headers[prop];  
              if (typeof value == "string") batch.req.setRequestHeader(prop, value);  
            }  
            if (!batch.headers["Content-Type"]) batch.req.setRequestHeader("Content-Type", "text/plain");  
          }  
          catch (ex) {  
            dwr.engine._handleWarning(batch, ex);  
          }  

在 batch.req.open前加验证

if(!batch.req) {  
                if (window.XMLHttpRequest) {  
                  batch.req = new XMLHttpRequest();  
                }  
                else if (window.ActiveXObject) {  
                  batch.req = dwr.engine.util.newActiveXObject(dwr.engine.transport.xhr.XMLHTTP);  
                }  
            }  

后，编辑后的js再打包在覆盖dwr的\org\directwebremoting\engine.js目录下，目前是这样解决的！