Fix IE redirect problem

conference.js

      * false.
      */
     isCallstatsEnabled () {
-        return room.isCallstatsEnabled();
+        return room && room.isCallstatsEnabled();
     },
     /**
      * Sends the given feedback through CallStats if enabled.

react/features/base/lib-jitsi-meet/_.web.js

 /* @flow */
 
+// Polyfill URL for Internet Explorer.
+import 'url-polyfill';
+
 declare var JitsiMeetJS: Object;
 
 export default JitsiMeetJS;

webpack.config.js

 
             loader: 'imports-loader?define=>false&this=>window',
             test: strophe
+        }, {
+            // Set scope to window for URL polyfill.
+
+            loader: 'imports-loader?this=>window',
+            test: /\/node_modules\/url-polyfill\/.*\.js$/
         }, {
             // Allow CSS to be imported into JavaScript.