[HarfBuzz] HarfBuzz-driven font fallback in Chrome

[Behdad Esfahbod]

For those not paying attention, Dominik landed HarfBuzz-driven font fallback
in Chrome recently:

  https://codereview.chromium.org/1397423004/

The idea is similar to what LibreOffice already does: shape with HarfBuzz and
the primary font, detect graphemes that need fallback and sort them into
contiguous runs, recursively handle them using the rest of the font fallback
chain...

Cheers, and nice job Dominik!
-- 
behdad
http://behdad.org/