Fix crash/assert on Mac when painting "small" QPushButtons.
Fix crash/assert on Mac when painting "small" QPushButtons.

A QPushButton with a height if (say) three pixels would cause
HIThemeGetButtonContentBounds ot return a rect with dimentions
{int_min, int_min, 0, 0}. Detect that case and return the button
rect instead.

Reviewed-by: Trust Me

radekp/qt,KDE/qt,RLovelett/qt,radekp/qt,RLovelett/qt,radekp/qt,igor-sfdc/qt-wk,KDE/qt,radekp/qt,RLovelett/qt,radekp/qt,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,KDE/qt,radekp/qt,igor-sfdc/qt-wk,KDE/qt,igor-sfdc/qt-wk,KDE/qt,KDE/qt,RLovelett/qt,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,KDE/qt,RLovelett/qt,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,radekp/qt,RLovelett/qt,RLovelett/qt,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,radekp/qt,igor-sfdc/qt-wk,igor-sfdc/qt-wk,radekp/qt,radekp/qt,igor-sfdc/qt-wk,igor-sfdc/qt-wk,RLovelett/qt,igor-sfdc/qt-wk,KDE/qt,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,RLovelett/qt,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,RLovelett/qt,RLovelett/qt