Remove Mac native font type members from FontPlatformData

Source/platform/fonts/SimpleFontData.h

Index: Source/platform/fonts/SimpleFontData.h
diff --git a/Source/platform/fonts/SimpleFontData.h b/Source/platform/fonts/SimpleFontData.h
index 2084209c073b84b8844138dc1c8ba84c16b17337..7d2e2cae190314382b80210d11a7d0997fc3d00b 100644
--- a/Source/platform/fonts/SimpleFontData.h
+++ b/Source/platform/fonts/SimpleFontData.h
@@ -133,7 +133,8 @@ public:
     void setMissingGlyphData(const GlyphData& glyphData) { m_missingGlyphData = glyphData; }
 
 #if OS(MACOSX)
-    NSFont* getNSFont() const { return m_platformData.font(); }
+    // TODO(dro): Where is this really used other than WebSubStringUtil.mm
+    const NSFont* getNSFont() const { return reinterpret_cast<const NSFont*>(m_platformData.ctFont()); }
 #endif
 
     bool canRenderCombiningCharacterSequence(const UChar*, size_t) const;