Change handling of unmatched surrogate pairs

Source/platform/fonts/UTF16TextIterator.h

 /*
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 50 matching lines @@
     }
 
     int offset() const { return m_offset; }
     const UChar* characters() const { return m_characters; }
     const UChar* glyphEnd() const { return m_characters + m_currentGlyphLength; }
     // FIXME: Only used by SimpleShaper, should be removed once the SimpleShaper
     // is removed.
     unsigned glyphLength() const { return m_currentGlyphLength; }
 
 private:
+    bool isValidSurrogatePair(UChar32&);
     bool consumeSurrogatePair(UChar32&);
     void consumeMultipleUChar();
 
     const UChar* m_characters;
     const UChar* m_charactersEnd;
     int m_offset;
     int m_endOffset;
     unsigned m_currentGlyphLength;
 };
 
 }
 
 #endif