bug 773165 - more robust removal of frameworker's iframe. r=gavin

toolkit/components/social/FrameWorker.jsm

@@ -212,10 +212,7 @@ FrameWorker.prototype = {
     // let pending events get delivered before actually removing the frame
     Services.tm.mainThread.dispatch(function deleteWorkerFrame() {
       // now nuke the iframe itself and forget everything about this worker.
-      let doc = Cc["@mozilla.org/appshell/appShellService;1"]
-                      .getService(Ci.nsIAppShellService)
-                      .hiddenDOMWindow.document;
-      doc.documentElement.removeChild(this.frame);
+      this.frame.parentNode.removeChild(this.frame)
       delete workerCache[this.url];
     }.bind(this), Ci.nsIThread.DISPATCH_NORMAL);
   }