add: return null; 
context:   getService: function (aProgID, aIID)    {      try        {          var iid = Components.interfaces[aIID];          return Components.classes[aProgID].getService(iid);        }      catch(e)        {        }    },
meta: 10234	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/10234/b6249a8f38a50426fc1b1cca10eceb5eb63cf981/nsJSComponentManager.js/buggy/xpfe/global/resources/content/nsJSComponentManager.js