Fetches a list of all feature tags in the given face's GSUB or GPOS table. Note that there might be duplicate feature tags, belonging to different script/language-system pairs of the table.
#hb_face_t to work upon
#HB_OT_TAG_GSUB or #HB_OT_TAG_GPOS
offset of the first feature tag to retrieve
Array of feature tags found in the table
Total number of feature tags.
Fetches a list of all feature tags in the given face's GSUB or GPOS table. Note that there might be duplicate feature tags, belonging to different script/language-system pairs of the table.