Fix substitution glyph class propagation

The old code was doing nothing.

Still got to find an example font+string that makes this matter, but
need this for fixing synthetic GDEF anyway.

src/hb-ot-layout-gsub-table.hh

@@ -212,9 +212,8 @@ struct Sequence
     TRACE_APPLY ();
     if (unlikely (!substitute.len)) return TRACE_RETURN (false);
 
-    if (c->property & HB_OT_LAYOUT_GLYPH_CLASS_LIGATURE)
-      c->guess_glyph_class (HB_OT_LAYOUT_GLYPH_CLASS_BASE_GLYPH);
-    c->replace_glyphs_be16 (1, substitute.len, (const uint16_t *) substitute.array);
+    unsigned int klass = c->property & HB_OT_LAYOUT_GLYPH_CLASS_LIGATURE ? HB_OT_LAYOUT_GLYPH_CLASS_BASE_GLYPH : 0;
+    c->replace_glyphs_be16 (1, substitute.len, (const uint16_t *) substitute.array, klass);
 
     return TRACE_RETURN (true);
   }
@@ -495,8 +494,7 @@ struct Ligature
       if (likely (c->buffer->info[skippy_iter.idx].codepoint != component[i])) return TRACE_RETURN (false);
     }
 
-    if (first_was_mark && found_non_mark)
-      c->guess_glyph_class (HB_OT_LAYOUT_GLYPH_CLASS_LIGATURE);
+    unsigned int klass = first_was_mark && found_non_mark ? HB_OT_LAYOUT_GLYPH_CLASS_LIGATURE : 0;
 
     /* Allocate new ligature id */
     unsigned int lig_id = allocate_lig_id (c->buffer);
@@ -504,7 +502,7 @@ struct Ligature
 
     if (skippy_iter.idx < c->buffer->idx + count) /* No input glyphs skipped */
     {
-      c->replace_glyphs_be16 (count, 1, (const uint16_t *) &ligGlyph);
+      c->replace_glyphs_be16 (count, 1, (const uint16_t *) &ligGlyph, klass);
     }
     else
     {

src/hb-ot-layout-gsubgpos-private.hh

@@ -222,31 +222,20 @@ struct hb_apply_context_t
 
 
 
-  inline void replace_glyph (hb_codepoint_t glyph_index) const
+  inline void replace_glyph (hb_codepoint_t glyph_index,
+			     unsigned int klass = 0) const
   {
-    clear_property ();
+    buffer->cur().props_cache() = klass; /*XXX if has gdef? */
     buffer->replace_glyph (glyph_index);
   }
   inline void replace_glyphs_be16 (unsigned int num_in,
 				   unsigned int num_out,
-				   const uint16_t *glyph_data_be) const
+				   const uint16_t *glyph_data_be,
+				   unsigned int klass = 0) const
   {
-    clear_property ();
+    buffer->cur().props_cache() = klass; /* XXX if has gdef? */
     buffer->replace_glyphs_be16 (num_in, num_out, glyph_data_be);
   }
-
-  inline void guess_glyph_class (unsigned int klass)
-  {
-    /* XXX if ! has gdef */
-    buffer->cur().props_cache() = klass;
-  }
-
-  private:
-  inline void clear_property (void) const
-  {
-    /* XXX if has gdef */
-    buffer->cur().props_cache() = 0;
-  }
 };