Respect fallback colors when interpolating text-decoration-color.

Source/core/rendering/style/RenderStyle.h

Index: Source/core/rendering/style/RenderStyle.h
diff --git a/Source/core/rendering/style/RenderStyle.h b/Source/core/rendering/style/RenderStyle.h
index c726d39bd9fef5e1c1d9a33c63140de738b6288b..28059772d8c484d643a7b3d0a2ee5def29142d38 100644
--- a/Source/core/rendering/style/RenderStyle.h
+++ b/Source/core/rendering/style/RenderStyle.h
@@ -1503,8 +1503,6 @@ public:
     bool lastChildState() const { return noninherited_flags.lastChildState; }
     void setLastChildState() { setUnique(); noninherited_flags.lastChildState = true; }
 
-    StyleColor visitedDependentDecorationStyleColor() const;
-    Color visitedDependentDecorationColor() const;
     Color visitedDependentColor(int colorProperty) const;
 
     void setHasExplicitlyInheritedProperties() { noninherited_flags.explicitInheritance = true; }
@@ -1776,6 +1774,7 @@ private:
     StyleColor visitedLinkTextFillColor() const { return rareInheritedData->visitedLinkTextFillColor(); }
     StyleColor visitedLinkTextStrokeColor() const { return rareInheritedData->visitedLinkTextStrokeColor(); }
 
+    StyleColor decorationColorIncludingFallback(bool visitedLink) const;
     Color colorIncludingFallback(int colorProperty, bool visitedLink) const;
 
     Color stopColor() const { return svgStyle().stopColor(); }