Remove value packing and custom style building for text-underline-position.

Source/core/rendering/style/StyleRareInheritedData.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *
  * 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
@@ skipping 109 matching lines @@
     unsigned textEmphasisMark : 3; // TextEmphasisMark
     unsigned textEmphasisPosition : 1; // TextEmphasisPosition
     unsigned m_textAlignLast : 3; // TextAlignLast
     unsigned m_textJustify : 2; // TextJustify
     unsigned m_textOrientation : 2; // TextOrientation
     unsigned m_textIndentLine : 1; // TextIndentEachLine
     unsigned m_textIndentType : 1; // TextIndentHanging
     unsigned m_lineBoxContain: 7; // LineBoxContain
     // CSS Image Values Level 3
     unsigned m_imageRendering : 3; // EImageRendering
-    unsigned m_textUnderlinePosition : 2; // TextUnderlinePosition
+    unsigned m_textUnderlinePosition : 1; // TextUnderlinePosition
     unsigned m_rubyPosition : 1; // RubyPosition
     unsigned m_touchActionDelay : 1; // TouchActionDelay
 
     // Though will-change is not itself an inherited property, the intent
     // expressed by 'will-change: contents' includes descendants.
     unsigned m_subtreeWillChangeContents : 1;
 
     AtomicString hyphenationString;
     short hyphenationLimitBefore;
     short hyphenationLimitAfter;
@@ skipping 11 matching lines @@
     RefPtr<AppliedTextDecorationList> appliedTextDecorations;
 
 private:
     StyleRareInheritedData();
     StyleRareInheritedData(const StyleRareInheritedData&);
 };
 
 } // namespace blink
 
 #endif // StyleRareInheritedData_h