Chromium for Mac cannot print surrogate pair in vertical writing mode

Source/platform/fonts/mac/GlyphPageTreeNodeMac.cpp

 /*
  * Copyright (C) 2006, 2007 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
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 extern "C" {
 void CGFontGetGlyphsForUnichars(CGFontRef font, const UniChar chars[], CGGlyph glyphs[], size_t length);
 }
 
 namespace WebCore {
 
 static bool shouldUseCoreText(UChar* buffer, unsigned bufferLength, const SimpleFontData* fontData)
 {
     if (fontData->platformData().isCompositeFontReference())
         return true;
+
+    // CoreText doesn't have vertical glyphs of surrogate pair characters.
+    // Therefore, we should not use CoreText, but this always returns horizontal glyphs.
+    // FIXME: We should use vertical glyphs. https://code.google.com/p/chromium/issues/detail?id=340173
+    if (bufferLength >= 2 && U_IS_SURROGATE(buffer[0]) && fontData->hasVerticalGlyphs()) {
+        ASSERT(U_IS_SURROGATE_LEAD(buffer[0]));
+        ASSERT(U_IS_TRAIL(buffer[1]));
+        return false;
+    }
+
     if (fontData->platformData().widthVariant() != RegularWidth || fontData->hasVerticalGlyphs()) {
         // Ideographs don't have a vertical variant or width variants.
         for (unsigned i = 0; i < bufferLength; ++i) {
             if (!Character::isCJKIdeograph(buffer[i]))
                 return true;
         }
     }
 
     return false;
 }
@@ skipping 101 matching lines @@
                     }
                 }
             }
         }
     }
 
     return haveGlyphs;
 }
 
 } // namespace WebCore