The not printing char ♙ was entered instead of my edit (some new text and a couple of references)
Also the first words that I typed and then deleted were inserted and the intervening text was deleted.
Using Firefox 22 under
ronald@ronald-xubuntu:~$ uname -a
Linux ronald-xubuntu 3.2.0-48-generic #74-Ubuntu SMP Thu Jun 6 19:43:26 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux