Add tab characters support in complex path

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 19 matching lines @@
 class PLATFORM_EXPORT UTF16TextIterator {
 public:
     // The passed in UChar pointer starts at 'offset'. The iterator operates on the range [offset, endOffset].
     // 'length' denotes the maximum length of the UChar array, which might exceed 'endOffset'.
     UTF16TextIterator(const UChar*, int length);
 
     // FIXME: The offset/endOffset fields are only used by the SimpleShaper,
     // remove once HarfBuzz is used for all text.
     UTF16TextIterator(const UChar*, int offset, int endOffset, int length);
 
+    bool atEnd() const { return m_offset >= m_endOffset; }
+
     inline bool consume(UChar32& character)
     {
         if (m_offset >= m_endOffset)
             return false;
 
         character = *m_characters;
         m_currentGlyphLength = 1;
 
         if (!U16_IS_SURROGATE(character) || consumeSurrogatePair(character)) {
             if (U_GET_GC_MASK(character) & U_GC_M_MASK)
@@ skipping 24 matching lines @@
     const UChar* m_characters;
     const UChar* m_charactersEnd;
     int m_offset;
     int m_endOffset;
     unsigned m_currentGlyphLength;
 };
 
 }
 
 #endif