Move isValid/isCurrentColor from Color to StyleColor

Source/core/rendering/RenderBox.cpp

Index: Source/core/rendering/RenderBox.cpp
diff --git a/Source/core/rendering/RenderBox.cpp b/Source/core/rendering/RenderBox.cpp
index f631c5cc430a6eb3afa0b32d99ad65d29ca9c6f0..12360edf7b267c5af49bc04fa11a77a32bebeedd 100644
--- a/Source/core/rendering/RenderBox.cpp
+++ b/Source/core/rendering/RenderBox.cpp
@@ -1171,7 +1171,7 @@ LayoutRect RenderBox::backgroundPaintedExtent() const
     ASSERT(hasBackground());
     LayoutRect backgroundRect = pixelSnappedIntRect(borderBoxRect());
 
-    Color backgroundColor = resolveColor(CSSPropertyBackgroundColor);
+    StyleColor backgroundColor = resolveStyleColor(CSSPropertyBackgroundColor);
     if (backgroundColor.isValid() && backgroundColor.alpha())
         return backgroundRect;
     if (!style()->backgroundLayers()->image() || style()->backgroundLayers()->next())
@@ -1186,7 +1186,7 @@ bool RenderBox::backgroundIsKnownToBeOpaqueInRect(const LayoutRect& localRect) c
     if (isBody() && skipBodyBackground(this))
         return false;
 
-    Color backgroundColor = resolveColor(CSSPropertyBackgroundColor);
+    StyleColor backgroundColor = resolveStyleColor(CSSPropertyBackgroundColor);
     if (!backgroundColor.isValid() || backgroundColor.hasAlpha())
         return false;
 
@@ -1304,7 +1304,7 @@ bool RenderBox::backgroundHasOpaqueTopLayer() const
 
     // If there is only one layer and no image, check whether the background color is opaque
     if (!fillLayer->next() && !fillLayer->hasImage()) {
-        Color bgColor = resolveColor(CSSPropertyBackgroundColor);
+        StyleColor bgColor = resolveStyleColor(CSSPropertyBackgroundColor);
         if (bgColor.isValid() && bgColor.alpha() == 255)
             return true;
     }