Move isValid/isCurrentColor from Color to StyleColor

Source/core/rendering/style/StyleMultiColData.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
  * 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
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  *
  */
 
 #ifndef StyleMultiColData_h
 #define StyleMultiColData_h
 
+#include "core/css/StyleColor.h"
 #include "core/platform/Length.h"
 #include "core/rendering/style/BorderValue.h"
 #include "core/rendering/style/RenderStyleConstants.h"
 #include <wtf/PassRefPtr.h>
 #include <wtf/RefCounted.h>
 
 namespace WebCore {
 
 // CSS3 Multi Column Layout
 
@@ skipping 12 matching lines @@
     {
         if (m_rule.style() == BNONE || m_rule.style() == BHIDDEN)
             return 0; 
         return m_rule.width();
     }
 
     float m_width;
     unsigned short m_count;
     float m_gap;
     BorderValue m_rule;
-    Color m_visitedLinkColumnRuleColor;
+    StyleColor m_visitedLinkColumnRuleColor;
 
     bool m_autoWidth : 1;
     bool m_autoCount : 1;
     bool m_normalGap : 1;
     unsigned m_columnSpan : 1;
     unsigned m_breakBefore : 2; // EPageBreak
     unsigned m_breakAfter : 2; // EPageBreak
     unsigned m_breakInside : 2; // EPageBreak
     unsigned m_axis : 2; // ColumnAxis
     unsigned m_progression : 2; // ColumnProgression
 
 private:
     StyleMultiColData();
     StyleMultiColData(const StyleMultiColData&);
 };
 
 } // namespace WebCore
 
 #endif // StyleMultiColData_h