Make scrolling on combobox work
Make scrolling on combobox work

Handles mouse scrolling event over combobox - scrolling up does the same
as pressing up arrow and scrolling down equals pressing down arrow.

Change-Id: I67adef46f201c0d4c88dabd5a717effc8f1e909d
Reviewed-by: J-P Nurmi <b84a892f57a298bb5dae653b4e188948a84d5549@digia.com>
Reviewed-by: David Edmundson <2fbbc4cabedec4253c2922f51eef7aa8c2146499@kde.org>

drgvond/qtquickcontrols,mizukusak/qtquickcontrols,drgvond/qtquickcontrols,mizukusak/qtquickcontrols,mizukusak/qtquickcontrols,kobolabs/qtquickcontrols,kobolabs/qtquickcontrols,kobolabs/qtquickcontrols,drgvond/qtquickcontrols