[HarfBuzz] Streamlining hb_font_t some more

[Simon Cozens]

On 10/10/2015 01:33, Jonathan Kew wrote:
> You probably want to be using the "typographic" metrics from the OS/2
> table, if present, with the hhea metrics as a fallback for fonts that
> don't have OS/2. (They're rare, but can exist at least on OS X.)

Hmm... that's something it doesn't look like Harfbuzz will help me with
at all.

Behdad, how would your suggestion to use the font's typographic metrics
work in practice? Do I need to go back to FT for this? Wasn't the whole
point to get away from FT?

S