Draft is present after posting via hotkeys in FF

Steps to reproduce:

1. Open any topic (discussion, QnA) and type some text in 'Message content' area.
2. Before appearing 'Draft just saved' (i.e. before 15 sec from start typing) post message via pressing hotkeys (Ctrl+Enter).
3. Refresh page

AR: Text of post appears in 'Message content' area, time counting 'saved ... seconds ago' appears under area.
ER: 'Message content' is empty, no draft in there.

Note:
Bug isn't reproduced in Google Chrome, Opera. If change focus area while typing post or make posting via pressing button bug also isn't reproduced (draft shouldn't be saved before posting).