Fetches the index of the first language tag fom language_tags that is present in the specified face's GSUB or GPOS table,
underneath the specified script index.
If none of the given language tags is found, `false` is returned and language_index is set to the default language index.
| face |
Face to work upon |
| table_tag |
|
| script_index |
The index of the requested script tag |
| language_count |
The number of languages in the specified script |
| language_tags |
The array of language tags |
| language_index |
The index of the requested language |
|
`true` if one of the given language tags is found, `false` otherwise |