Convert animation and renderer code to know about BorderImageLength

Source/platform/LengthOrNumber.h

 /*
     Copyright (c) 2013, Opera Software ASA. 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 30 matching lines @@
     }
 
     bool isNumber() const { return m_length.isRelative(); }
     bool isLength() const { return !isNumber(); }
 
     const Length& length() const { ASSERT(isLength()); return m_length; }
     Length& length() { ASSERT(isLength()); return m_length; }
 
     double number() const { ASSERT(isNumber()); return m_length.value(); }
 
-    Length unifiedLength() const { return m_length; }
-
     bool operator==(const LengthOrNumber& o) const
     {
         return m_length == o.m_length;
     }
 
     bool isZero() const
     {
         return m_length.isZero();
     }
 
 private:
     Length m_length;
 };
 
 } // namespace WebCore
 
 #endif // LengthOrNumber_h