Remove the "horizontal-bt" value from -webkit-writing-mode

third_party/WebKit/Source/platform/LengthBox.cpp

 /*
  * Copyright (c) 2012, Google Inc. 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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 30 matching lines @@
 const Length& LengthBox::logicalRight(WritingMode writingMode) const
 {
     return isHorizontalWritingMode(writingMode) ? m_right : m_bottom;
 }
 
 const Length& LengthBox::before(WritingMode writingMode) const
 {
     switch (writingMode) {
     case TopToBottomWritingMode:
         return m_top;
-    case BottomToTopWritingMode:
-        return m_bottom;
     case LeftToRightWritingMode:
         return m_left;
     case RightToLeftWritingMode:
         return m_right;
     }
     ASSERT_NOT_REACHED();
     return m_top;
 }
 
 const Length& LengthBox::after(WritingMode writingMode) const
 {
     switch (writingMode) {
     case TopToBottomWritingMode:
         return m_bottom;
-    case BottomToTopWritingMode:
-        return m_top;
     case LeftToRightWritingMode:
         return m_right;
     case RightToLeftWritingMode:
         return m_left;
     }
     ASSERT_NOT_REACHED();
     return m_bottom;
 }
 
 const Length& LengthBox::start(WritingMode writingMode, TextDirection direction) const
 {
     if (isHorizontalWritingMode(writingMode))
         return isLeftToRightDirection(direction) ? m_left : m_right;
     return isLeftToRightDirection(direction) ? m_top : m_bottom;
 }
 
 const Length& LengthBox::end(WritingMode writingMode, TextDirection direction) const
 {
     if (isHorizontalWritingMode(writingMode))
         return isLeftToRightDirection(direction) ? m_right : m_left;
     return isLeftToRightDirection(direction) ? m_bottom : m_top;
 }
 
 } // namespace blink