Override GetPixelSize on OS X as the base impl creates a wxScreenDC each time, which causes a significant performance hit.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@42416 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/mac/carbon/font.h

@@ -56,6 +56,7 @@ public:
 
     // implement base class pure virtuals
     virtual int GetPointSize() const;
+    virtual wxSize GetPixelSize() const;
     virtual int GetFamily() const;
     virtual int GetStyle() const;
     virtual int GetWeight() const;