Roll harfbuzz-ng to 0.9.40

third_party/harfbuzz-ng/src/hb-buffer.cc

 /*
  * Copyright © 1998-2004  David Turner and Werner Lemberg
  * Copyright © 2004,2007,2009,2010  Red Hat, Inc.
  * Copyright © 2011,2012  Google, Inc.
  *
  *  This is part of HarfBuzz, a text shaping library.
  *
  * Permission is hereby granted, without written agreement and without
  * license or royalty fees, to use, copy, modify, and distribute this
  * software and its documentation for any purpose, provided that the
@@ skipping 425 matching lines @@
     if (cluster_start <= info[i].cluster && info[i].cluster < cluster_end)
       info[i].mask = (info[i].mask & not_mask) | value;
 }
 
 void
 hb_buffer_t::reverse_range (unsigned int start,
                             unsigned int end)
 {
   unsigned int i, j;
 
-  if (start == end - 1)
+  if (end - start < 2)
     return;
 
   for (i = start, j = end - 1; i < j; i++, j--) {
     hb_glyph_info_t t;
 
     t = info[i];
     info[i] = info[j];
     info[j] = t;
   }
 
@@ skipping 1128 matching lines @@
 
   unsigned int start = 0;
   unsigned int end;
   for (end = start + 1; end < count; end++)
     if (info[start].cluster != info[end].cluster) {
       normalize_glyphs_cluster (buffer, start, end, backward);
       start = end;
     }
   normalize_glyphs_cluster (buffer, start, end, backward);
 }