Function position_mark

fn position_mark(
    _: &hb_ot_shape_plan_t,
    face: &hb_font_t<'_>,
    direction: Direction,
    glyph: GlyphId,
    pos: &mut GlyphPosition,
    base_extents: &mut hb_glyph_extents_t,
    combining_class: CanonicalCombiningClass,
)