Serialize the font index.

src/ports/SkFontHost_fontconfig.cpp

 /*
  * Copyright 2008 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkFontConfigInterface.h"
 #include "SkFontConfigTypeface.h"
 #include "SkFontDescriptor.h"
@@ skipping 147 matching lines @@
         }
         stream = fci->openStream(this->getIdentity());
         *ttcIndex = this->getIdentity().fTTCIndex;
     }
     return stream;
 }
 
 void FontConfigTypeface::onGetFontDescriptor(SkFontDescriptor* desc,
                                              bool* isLocalStream) const {
     desc->setFamilyName(this->getFamilyName());
+    desc->setFontFileIndex(this->getIdentity().fTTCIndex);
     *isLocalStream = SkToBool(this->getLocalStream());
 }