Revert of Cherry pick disabled unicode compatibility decomposition into HarfBuzz

third_party/harfbuzz-ng/src/hb-ot-shape-normalize.cc

 /*
  * 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
  * above copyright notice and the following two paragraphs appear in
  * all copies of this software.
@@ skipping 153 matching lines @@
     if (likely (b)) {
       output_char (buffer, b, b_glyph);
       return 2;
     }
     return 1;
   }
 
   return 0;
 }
 
+/* Returns 0 if didn't decompose, number of resulting characters otherwise. */
+static inline unsigned int
+decompose_compatibility (const hb_ot_shape_normalize_context_t *c, hb_codepoint_t u)
+{
+  unsigned int len, i;
+  hb_codepoint_t decomposed[HB_UNICODE_MAX_DECOMPOSITION_LEN];
+  hb_codepoint_t glyphs[HB_UNICODE_MAX_DECOMPOSITION_LEN];
+
+  len = c->buffer->unicode->decompose_compatibility (u, decomposed);
+  if (!len)
+    return 0;
+
+  for (i = 0; i < len; i++)
+    if (!c->font->get_glyph (decomposed[i], 0, &glyphs[i]))
+      return 0;
+
+  for (i = 0; i < len; i++)
+    output_char (c->buffer, decomposed[i], glyphs[i]);
+
+  return len;
+}
+
 static inline void
 decompose_current_character (const hb_ot_shape_normalize_context_t *c, bool shortest)
 {
   hb_buffer_t * const buffer = c->buffer;
   hb_codepoint_t u = buffer->cur().codepoint;
   hb_codepoint_t glyph;
 
   /* Kind of a cute waterfall here... */
   if (shortest && c->font->get_glyph (u, 0, &glyph))
     next_char (buffer, glyph);
   else if (decompose (c, shortest, u))
     skip_char (buffer);
   else if (!shortest && c->font->get_glyph (u, 0, &glyph))
     next_char (buffer, glyph);
+  else if (decompose_compatibility (c, u))
+    skip_char (buffer);
   else
     next_char (buffer, glyph); /* glyph is initialized in earlier branches. */
 }
 
 static inline void
 handle_variation_selector_cluster (const hb_ot_shape_normalize_context_t *c, unsigned int end, bool short_circuit)
 {
   /* TODO Currently if there's a variation-selector we give-up, it's just too hard. */
   hb_buffer_t * const buffer = c->buffer;
   hb_font_t * const font = c->font;
@@ skipping 185 matching lines @@
 
     /* Blocked, or doesn't compose. */
     buffer->next_glyph ();
 
     if (_hb_glyph_info_get_modified_combining_class (&buffer->prev()) == 0)
       starter = buffer->out_len - 1;
   }
   buffer->swap_buffers ();
 
 }