Move isValid/isCurrentColor from Color to StyleColor

Source/core/rendering/style/StyleMultiColData.h

Index: Source/core/rendering/style/StyleMultiColData.h
diff --git a/Source/core/rendering/style/StyleMultiColData.h b/Source/core/rendering/style/StyleMultiColData.h
index 1b50250a1f8dc970d53ce025dd543c406f4c3d09..d4531b34c98eabcdef49381e3c882c35ee9dfd64 100644
--- a/Source/core/rendering/style/StyleMultiColData.h
+++ b/Source/core/rendering/style/StyleMultiColData.h
@@ -25,6 +25,7 @@
 #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"
@@ -57,7 +58,7 @@ public:
     unsigned short m_count;
     float m_gap;
     BorderValue m_rule;
-    Color m_visitedLinkColumnRuleColor;
+    StyleColor m_visitedLinkColumnRuleColor;
 
     bool m_autoWidth : 1;
     bool m_autoCount : 1;