message: Hoist upgrade handler into current scope by using an arrow function
diff: @@ -52,7 +52,7 @@ export default class Passport {
  }
  });
  - function socketUpgradeHandler () {
  + const socketUpgradeHandler = () => {
  socket.io.engine.on('upgrade', () => {
  debug('Socket upgrading');
  @@ -73,7 +73,7 @@ export default class Passport {
  });
  }
  });
  - }
  + };
  if (socket.io && socket.io.engine) {
  socketUpgradeHandler();
  