pub fn gsub_apply_arabic(
gsub_cache: &LayoutCache<GSUB>,
gsub_table: &LayoutTable<GSUB>,
gdef_table: Option<&GDEFTable>,
script_tag: u32,
lang_tag: Option<u32>,
raw_glyphs: &mut Vec<RawGlyph<()>>
) -> Result<(), ShapingError>