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..3221f3bfdb872845b19bd0c35356e79e3363ec03 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 isCustomIdentValue() const { return m_classType == CustomIdentClass; }
     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; }
@@ -109,13 +112,14 @@ public:
     // 'source\wtf\refcounted.h' by using msvc.
     ~CSSValue() { }
 
-protected:
-
     static const size_t ClassTypeBits = 6;
     enum ClassType {
         PrimitiveClass,
         CounterClass,
         QuadClass,
+        CustomIdentClass,
+        StringClass,
+        URIClass,
         ValuePairClass,
 
         // Image classes.
@@ -160,6 +164,7 @@ protected:
         // Do not append non-list class types here.
     };
 
+protected:
     static const size_t ValueListSeparatorBits = 2;
     enum ValueListSeparator {
         SpaceSeparator,