Add toSVGColor|Paint() to cleanup static_cast<>, and use it

Source/core/svg/SVGColor.h

Index: Source/core/svg/SVGColor.h
diff --git a/Source/core/svg/SVGColor.h b/Source/core/svg/SVGColor.h
index 554fe77052b62af0e49a077e244593801cd12778..42875ed651673d783af09466b7e4140f94b1be03 100644
--- a/Source/core/svg/SVGColor.h
+++ b/Source/core/svg/SVGColor.h
@@ -93,6 +93,22 @@ private:
     SVGColorType m_colorType;
 };
 
+// This will catch anyone doing an unnecessary cast.
+SVGColor* toSVGColor(const SVGColor*);
+
+inline SVGColor* toSVGColor(CSSValue* value)
+{
+    ASSERT_WITH_SECURITY_IMPLICATION(!value || value->isSVGColor());
+    return static_cast<SVGColor*>(value);
+}
+
+inline const SVGColor* toSVGColor(const CSSValue* value)
+{
+    ASSERT_WITH_SECURITY_IMPLICATION(!value || value->isSVGColor());
+    return static_cast<const SVGColor*>(value);
+}
+
+
 } // namespace WebCore
 
 #endif // SVGColor_h