add: return null; 
context:   getService: function (aProgID, aIID)    {      try        {          var iid = Components.interfaces[aIID];          return Components.classes[aProgID].getService(iid);        }      catch(e)        {        }    },
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/5ef90bd4607b8c60f53f1bd234fee4b2f57c5e5c/nsJSComponentManager.js/buggy/xpfe/global/resources/content/nsJSComponentManager.js