Split out String, URI and CustomIdent from CSSPrimitiveValue

Source/core/css/CSSValue.h

Index: Source/core/css/CSSValue.h
diff --git a/Source/core/css/CSSValue.h b/Source/core/css/CSSValue.h
index 27d63e01564d854464e00aa5e073e9b2723ef3ce..1f31892247bf7cae31a70a4a8d36fcc43affbb8f 100644
--- a/Source/core/css/CSSValue.h
+++ b/Source/core/css/CSSValue.h
@@ -72,6 +72,7 @@ public:
     bool isFontFeatureValue() const { return m_classType == FontFeatureClass; }
     bool isFontFaceSrcValue() const { return m_classType == FontFaceSrcClass; }
     bool isFunctionValue() const { return m_classType == FunctionClass; }
+    bool isIdentValue() const { return m_classType == IdentClass; }
     bool isImageGeneratorValue() const { return m_classType >= CanvasClass && m_classType <= RadialGradientClass; }
     bool isGradientValue() const { return m_classType >= LinearGradientClass && m_classType <= RadialGradientClass; }
     bool isImageSetValue() const { return m_classType == ImageSetClass; }
@@ -87,6 +88,8 @@ public:
     bool isRadialGradientValue() const { return m_classType == RadialGradientClass; }
     bool isReflectValue() const { return m_classType == ReflectClass; }
     bool isShadowValue() const { return m_classType == ShadowClass; }
+    bool isStringValue() const { return m_classType == StringClass; }
+    bool isURIValue() const { return m_classType == URIClass; }
     bool isCubicBezierTimingFunctionValue() const { return m_classType == CubicBezierTimingFunctionClass; }
     bool isStepsTimingFunctionValue() const { return m_classType == StepsTimingFunctionClass; }
     bool isGridTemplateAreasValue() const { return m_classType == GridTemplateAreasClass; }
@@ -116,6 +119,9 @@ protected:
         PrimitiveClass,
         CounterClass,
         QuadClass,
+        IdentClass,
+        StringClass,
+        URIClass,
         ValuePairClass,
 
         // Image classes.