sd_ass: remove unneeded ontop variable

Missed in 3250f6e. Note that the
hardcoded ass alignment value is not used anymore as of that commit, but
we should ideally be moving towards secondary subs actually being
customizable via ASS anyways.

sub/sd_ass.c

@@ -49,7 +49,6 @@ struct sd_ass_priv {
     struct sd_filter **filters;
     int num_filters;
     bool clear_once;
-    bool on_top;
     struct mp_ass_packer *packer;
     struct sub_bitmap_copy_cache *copy_cache;
     char last_text[500];
@@ -562,8 +561,7 @@ static struct sub_bitmaps *get_bitmaps(struct sd *sd, struct mp_osd_res dim,
 {
     struct sd_ass_priv *ctx = sd->priv;
     struct mp_subtitle_opts *opts = sd->opts;
-    bool no_ass = !opts->ass_enabled || ctx->on_top ||
-                  opts->ass_style_override == 5 || order == 1;
+    bool no_ass = !opts->ass_enabled || opts->ass_style_override == 5 || order == 1;
     bool converted = ctx->is_converted || no_ass;
     ASS_Track *track = no_ass ? ctx->shadow_track : ctx->ass_track;
     ASS_Renderer *renderer = ctx->ass_renderer;
@@ -786,9 +784,6 @@ static void fill_plaintext(struct sd *sd, double pts)
 
     bstr dst = {0};
 
-    if (ctx->on_top)
-        bstr_xappend(NULL, &dst, bstr0("{\\a6}"));
-
     while (*text) {
         if (*text == '{')
             bstr_xappend(NULL, &dst, bstr0("\\"));