QPushButton: draw label using the stylesheet's font.

The RenderRule for the stylesheet has the correct font information, it
just wasn't being set on the painter that draws the label.

Task-number: QTBUG-8990

Change-Id: I7cbaffc570421db04ebf3254cb6a21a68f7b868b
Reviewed-by: Andy Shaw <andy.shaw@digia.com>
Reviewed-by: Jens Bache-Wiig <jens.bache-wiig@digia.com>
QFusionStyle: support transient scrollbars

QFusionStyle doesn't make scrollbars transient by default,
but the feature can be enabled with a proxy style:

class MyProxyStyle : public QProxyStyle
{
public:
    int styleHint(StyleHint sh, const QStyleOption *opt = 0,
                  const QWidget *w = 0, QStyleHintReturn *ret = 0) const
    {
        if (sh == QStyle::SH_ScrollBar_Transient)
            return 1;
        return QProxyStyle::styleHint(sh, opt, w, ret);
    }
};

Change-Id: Ibf169e219ad920cbe7edb06e128e09ed4d8faf96
Reviewed-by: Jens Bache-Wiig <jens.bache-wiig@digia.com>