El is not defined. It means to use Element in the line: "delete El.cache[me.id];".

Original:
PHP Code:
        replaceWith: function(el){
            var 
me this,
                
Element Ext.Element;
            if(
el.nodeType || el.dom){
                
el GETDOM(el);
                
me.dom.parentNode.insertBefore(elme.dom);
            }else{
                
el DH.insertBefore(me.domel);
            }
            
            
delete El.cache[me.id];
            
Ext.removeNode(me.dom);      
            
me.id Ext.id(me.dom el);
            return 
Element.cache[me.id] = me;        
        } 
Proposed:
PHP Code:
        replaceWith: function(el){
            var 
me this,
                
Element Ext.Element;
            if(
el.nodeType || el.dom){
                
el GETDOM(el);
                
me.dom.parentNode.insertBefore(elme.dom);
            }else{
                
el DH.insertBefore(me.domel);
            }
            
            
delete Element.cache[me.id];
            
Ext.removeNode(me.dom);      
            
me.id Ext.id(me.dom el);
            return 
Element.cache[me.id] = me;        
        }