Move isValid/isCurrentColor from Color to StyleColor

Source/core/css/resolver/FilterOperationResolver.cpp

Index: Source/core/css/resolver/FilterOperationResolver.cpp
diff --git a/Source/core/css/resolver/FilterOperationResolver.cpp b/Source/core/css/resolver/FilterOperationResolver.cpp
index 238e9517c19636a97d3c73fb8fe6d0706a135fae..5a80c3eba86d1d62932c74f7998d36b0ee964416 100644
--- a/Source/core/css/resolver/FilterOperationResolver.cpp
+++ b/Source/core/css/resolver/FilterOperationResolver.cpp
@@ -493,11 +493,11 @@ bool FilterOperationResolver::createFilterOperations(CSSValue* inValue, const Re
             ShadowValue* item = static_cast<ShadowValue*>(cssValue);
             IntPoint location(item->x->computeLength<int>(style, rootStyle, zoomFactor), item->y->computeLength<int>(style, rootStyle, zoomFactor));
             int blur = item->blur ? item->blur->computeLength<int>(style, rootStyle, zoomFactor) : 0;
-            Color color;
+            StyleColor shadowColor;
             if (item->color)
-                color = state.document()->textLinkColors().colorFromPrimitiveValue(item->color.get(), state.style()->visitedDependentColor(CSSPropertyColor));
+                shadowColor = state.document()->textLinkColors().colorFromPrimitiveValue(item->color.get());
 
-            operations.operations().append(DropShadowFilterOperation::create(location, blur, color.isValid() ? color : Color::transparent, operationType));
+            operations.operations().append(DropShadowFilterOperation::create(location, blur, shadowColor.isValid() ? shadowColor.color() : Color::transparent, operationType));
             break;
         }
         case CSSFilterValue::UnknownFilterOperation: