ASSERT that characterIndexForXPosition has a GlyphToCharacter vector

Source/platform/fonts/shaping/HarfBuzzShaper.cpp

 /*
  * Copyright (c) 2012 Google Inc. All rights reserved.
  * Copyright (C) 2013 BlackBerry Limited. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 299 matching lines @@
         currentX = nextX;
         ++glyphIndex;
     }
 
     return rtl() ? 0 : m_numCharacters;
 }
 
 float HarfBuzzShaper::HarfBuzzRun::xPositionForOffset(unsigned offset)
 {
     ASSERT(offset < m_numCharacters);
+    ASSERT(hasGlyphToCharacterIndexes());
     unsigned glyphIndex = 0;
     float position = 0;
     if (rtl()) {
         while (glyphIndex < m_numGlyphs && m_glyphToCharacterIndexes[glyphIndex] > offset) {
             position += m_advances[glyphIndex];
             ++glyphIndex;
         }
         // For RTL, we need to return the right side boundary of the character.
         // Add advance of glyphs which are part of the character.
         while (glyphIndex < m_numGlyphs - 1 && m_glyphToCharacterIndexes[glyphIndex] == m_glyphToCharacterIndexes[glyphIndex + 1]) {
@@ skipping 815 matching lines @@
         fromX = 0;
     if (!foundToX)
         toX = m_run.rtl() ? 0 : m_totalWidth;
 
     if (fromX < toX)
         return FloatRect(point.x() + fromX, point.y(), toX - fromX, height);
     return FloatRect(point.x() + toX, point.y(), fromX - toX, height);
 }
 
 } // namespace blink