It appears that CTFontCreateCopyWithAttributes and
CTFontCreateCopyWithSymbolicTraits share similar issues with the default
font on OSX10.10. CTFontCreateWithFontDescriptor cannot be used as
it will not work with webfonts. Since this is all low-level use, create the
CTFonts from the underlying CGFonts directly.
BUG=chromium:524646
Committed: https://skia.googlesource.com/skia/+/d3296717b9d0930237be3502b82ab94d0b4d177f
Review URL: https://codereview.chromium.org/1344213004