Autosave while typing not working if online editor enable

Steps to reproduce:
1. Change autosave interval to "-1" in settings/override/autosave.ini.append.php

<?php /*
[AutosaveSettings]
Interval=-1
*/ ?>

2. Clear all caches
3. Login to admin interface
4. On Content structure create a new Article
5. Verify that while typing a character in the title the "Draft is being saved message" appears
6. Verify that online editor is enabled in summary field
7. Start typing on summary and verify that no message is present in autosave bar
8. Disable de online editor
9. Start typing in summary field and verify that now the "Draft is being saved message" appears for every character you type