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CoreText doesn't have vertical glyphs of surrogate pair characters, and
we draw broken glyphs. On Safari, wkGetVerticalGlyphsForCharacters
returns true, and we use the glyphs which is returned from the
SPI. However, according to the description of r149659,
WKGetVerticalGlyphsForCharacters() just returns false on
Chromium. Therefore, we cannot get vertical glyphs from Mac API/SPI.

To work around that, we should not use CoreText for surrogate pair
characters in vertical writing mode, but this always returns horizontal
glyphs.

BUG=337080

Review URL: https://codereview.chromium.org/145473002

git-svn-id: svn://svn.chromium.org/blink/trunk@166358 bbb929c8-8fbe-4397-9dbb-9b2b20218538