Move isValid/isCurrentColor from Color to StyleColor

Source/core/rendering/RenderMenuList.cpp

 /*
  * This file is part of the select element renderer in WebCore.
  *
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  *               2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.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 473 matching lines @@
 {
     const Vector<HTMLElement*>& listItems = selectElement()->listItems();
     if (listIndex >= listItems.size()) {
         itemBackgroundColor = resolveColor(CSSPropertyBackgroundColor);
         itemHasCustomBackgroundColor = false;
         return;
     }
     HTMLElement* element = listItems[listIndex];
 
     Color backgroundColor;
-    if (element->renderStyle())
+    if (element->renderStyle()) {
         backgroundColor = resolveColor(element->renderStyle(), CSSPropertyBackgroundColor);
-    itemHasCustomBackgroundColor = backgroundColor.isValid() && backgroundColor.alpha();
+        itemHasCustomBackgroundColor = backgroundColor.alpha();
+    } else {
+        itemHasCustomBackgroundColor = false;
+    }
+
     // If the item has an opaque background color, return that.
     if (!backgroundColor.hasAlpha()) {
         itemBackgroundColor = backgroundColor;
         return;
     }
 
     // Otherwise, the item's background is overlayed on top of the menu background.
     backgroundColor = resolveColor(CSSPropertyBackgroundColor).blend(backgroundColor);
     if (!backgroundColor.hasAlpha()) {
         itemBackgroundColor = backgroundColor;
@@ skipping 100 matching lines @@
 {
     setTextFromOption(selectElement()->listToOptionIndex(listIndex));
 }
 
 FontSelector* RenderMenuList::fontSelector() const
 {
     return document()->styleResolver()->fontSelector();
 }
 
 }