Previously the animation paint events could overlap if the framerate
estimates were off by more than 1 event. Furthermore the duration could
be negative or 0, with a potential crash in the latter case. Also it's
a bad idea to change the server-provided framerate to suit our estimated
durations.

Change-Id: I14da0855d7248a6ef32509572caa439ebb2d430e
Reviewed-by: Kai Koehne <kai.koehne@digia.com>