Problems to create an account with old Firefox (16.0.2)

In a Firefox v.16.0.2 running over a mac (OS X 10.5.8) I was not able to go beyond the account creation page. After hitting the button to create (right after the passphrase) the button kept blinking "joining" but did not finished the procedure.
In Chrome it used flawlessly.

Start by checking whether account creation can still be reproduced in Firefox 16.0.2 on OS X 10.5.8, then compare the same flow in Chrome as reported. Done means the account creation procedure completes instead of remaining on “joining”; the issue provides no file or test entry point.

Written by the indexing model from the issue text.