Split out String, URI and CustomIdent from CSSPrimitiveValue

Source/core/css/parser/CSSParserValues.h

Index: Source/core/css/parser/CSSParserValues.h
diff --git a/Source/core/css/parser/CSSParserValues.h b/Source/core/css/parser/CSSParserValues.h
index 3ff1b879263a84733bd76b739e211e7e670da503..1cfa3b6516eaa9012344742b7962bbdb22487742 100644
--- a/Source/core/css/parser/CSSParserValues.h
+++ b/Source/core/css/parser/CSSParserValues.h
@@ -63,6 +63,8 @@ struct CSSParserValue {
         DimensionList = 0x100006,
         // Represents a unicode range by a pair of UChar32 values
         UnicodeRange = 0x100007,
+        URI = 0x100008,
+        String = 0x100009,
     };
     int m_unit;
     CSSPrimitiveValue::UnitType unit() const { return static_cast<CSSPrimitiveValue::UnitType>(m_unit); }