Mac OS X: Fix possible crash when using some TrueType fonts.

This is just a workaround. We simply avoid removing the custom font
(intentionally leak it, a small price to pay) because otherwise it will
invalidate Qt's font cache, which in turns trigger the crash at
CoreText's CTFontCopyGraphicsFont.

http://code.google.com/p/phantomjs/issues/detail?id=690

src/qt/src/3rdparty/webkit/Source/WebCore/platform/graphics/qt/FontCustomPlatformDataQt.cpp

@@ -32,7 +32,11 @@ namespace WebCore {
 
 FontCustomPlatformData::~FontCustomPlatformData()
 {
+#if !defined(Q_OS_MAC)
+    // On Mac OS X, do not remove the font because it may crash.
+    // For details, see issue 690 (http://code.google.com/p/phantomjs/issues/detail?id=690).
     QFontDatabase::removeApplicationFont(m_handle);
+#endif
 }
 
 FontPlatformData FontCustomPlatformData::fontPlatformData(int size, bool bold, bool italic, FontOrientation, TextOrientation, FontWidthVariant, FontRenderingMode)