The changed documents get searched for symbols when either a limit of
10 pending documents is reached, or when the filter is asked to return
all matches.

Change-Id: Ic18fc66b0a802165fdd8a028bd13d0ce11524510
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@digia.com>
Reviewed-by: Eike Ziller <eike.ziller@digia.com>