rem: this.browser.loadURI(frameURL, makeURI(doc.referrer)); 
add: var referrer = doc.referrer; this.browser.loadURI(frameURL, referrer ? makeURI(referrer) : null); 
context:   showOnlyThisFrame: function() {    var doc = this.target.ownerDocument;    var frameURL = doc.documentURIObject.spec;    urlSecurityCheck(frameURL, this.browser.contentPrincipal,                     Ci.nsIScriptSecurityManager.DISALLOW_SCRIPT);    this.browser.loadURI(frameURL, makeURI(doc.referrer));  },
meta: 10520	/local1/tlutelli/issta_data/temp/all_js/javascript/2007_temp/2007/10520/4738fd623a278e8b71bb5f921df913eff2863a00/nsContextMenu.js/clean/browser/base/content/nsContextMenu.js