Distinguish no internet connection error

[balinterdi]

In our client application, we want to be able to set apart the case where the user does not have an internet connection and display a message accordingly on the login screen.

It seems to me though that the error status code for the "no connection" error is transformed into a 401 because of this line that fixes an IE 10 error, judging from the code comment.

Is there a way to distinguish the "no connection" error from other errors and have everything also work under IE10?

[pose]

Reproduction steps:

1. create a login using auth0.js
2. disconnect from the network
3. try to login

Notify @patrickyoung when this is fixed.