add: return null; 
context: function findFirstTreeItem(tree) {  var children = tree.childNodes;    var treechildren;  for (var i=0;i<children.length; i++) {    if (children[i].localName == "treechildren") {      treechildren = children[i];      break;    }  }  var children = treechildren.childNodes;  for (var i=0; i<children.length; i++) {    if (children[i].localName == "treeitem")      return children[i];  }}
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/a54c1e81862552407f4d1ce2150887df825b7ea1/AccountManager.js/buggy/mailnews/base/prefs/resources/content/AccountManager.js