Process touch events in sorted order.

We are mapping a single QTouchEvent to
multiple MotionEventQt for Chromium.
For gesture recognition it is important
that these motion events are being processed
in a sorted manner, as a move event might
trigger a different gesture depending on
how many ACTION_DOWN or ACTION_POINTER_DOWN
were received before.

It is particularly illegal to process an ACTION_MOVE
with multiple touch points without having received
a ACTION_POINTER_DOWN before.

Change-Id: I75d22dd845774a14b5f590e0e0ce46263c4a49f4
Reviewed-by: Jocelyn Turcotte <jocelyn.turcotte@digia.com>
Reviewed-by: Andras Becsi <andras.becsi@digia.com>