Firefox 44 (and Chrome in future) may reject some web fonts that were previously accepted

Just a quick heads up, Firefox 44, coming Jan 26 2016 (
https://developer.mozilla.org/en-US/Firefox/Releases/44) updates OTS to
reject fonts if it rejected any of { GDEF, GSUB, GPOS }. Chrome will pick
this up at some point as well.

Previously OTS would drop the table(s) but accept the font so it would work
as a web font, albeit potentially with odd behavior due to the missing
tables.

This change causes some fonts that were previously accepted to be rejected
by the browser. If so, those fonts will require updates to continue to work
as web fonts.

See https://github.com/khaledhosny/ots/issues/74 for additional context
around the OTS change.

Rod S