On a related note, there is a number of fonts with Latin an Cyrillic and/or
Greek alphabets which provide all features such as kern, smcp, liga etc.
only in the latn script even if those features affect also the Cyrillic
and/or Grrek fonts. This is mostly due to the tool used to produce them.
It turns out that some legacy Thai fonts provide OpenType substitution features
to implement mark positioning, but (incorrectly) put those features/lookups
under the 'latn' script tag instead of using 'thai' (or possibly 'DFLT'). See
https://bugzilla.mozilla.org/show_bug.cgi?id=719366 for an
