Fold CSSParser::colorFromRGBColorString into only user

Source/core/css/parser/CSSParser.h

Index: Source/core/css/parser/CSSParser.h
diff --git a/Source/core/css/parser/CSSParser.h b/Source/core/css/parser/CSSParser.h
index f0cc0f9eccb4933326a5174d9ad66a7417132bea..9e4a7a5d4286a34ceb9f4f9eb88e2fafa95fcd50 100644
--- a/Source/core/css/parser/CSSParser.h
+++ b/Source/core/css/parser/CSSParser.h
@@ -51,7 +51,6 @@ public:
     // can set it to a default color and ignore the boolean result.
     static bool parseColor(RGBA32& color, const String&, bool strict = false);
     static bool parseSystemColor(RGBA32& color, const String&);
-    static StyleColor colorFromRGBColorString(const String&);
 
     static void parseSheetForInspector(const CSSParserContext&, StyleSheetContents*, const String&, CSSParserObserver&);
     static void parseDeclarationListForInspector(const CSSParserContext&, const String&, CSSParserObserver&);