Fetches a list of feature variations in the specified face's GSUB table or GPOS table, at the specified variation coordinates.
#hb_face_t to work upon
#HB_OT_TAG_GSUB or #HB_OT_TAG_GPOS
The variation coordinates to query
The array of feature variations found for the query
true if feature variations were found, false otherwise.
Fetches a list of feature variations in the specified face's GSUB table or GPOS table, at the specified variation coordinates.