Support 'paint-order' from SVG2.

Source/core/css/CSSPrimitiveValueMappings.h

Index: Source/core/css/CSSPrimitiveValueMappings.h
diff --git a/Source/core/css/CSSPrimitiveValueMappings.h b/Source/core/css/CSSPrimitiveValueMappings.h
index d727334b87451b9418f10c68c5194a52b95e6229..17c6d5d3fca9a06fafe0b026d827c3415bb71e02 100644
--- a/Source/core/css/CSSPrimitiveValueMappings.h
+++ b/Source/core/css/CSSPrimitiveValueMappings.h
@@ -4512,6 +4512,47 @@ template<> inline CSSPrimitiveValue::operator EVectorEffect() const
     return VE_NONE;
 }
 
+template<> inline CSSPrimitiveValue::CSSPrimitiveValue(EPaintOrder e)
+    : CSSValue(PrimitiveClass)
+{
+    m_primitiveUnitType = CSS_IDENT;
+    switch (e) {
+    case PO_NORMAL:
+        m_value.ident = CSSValueNormal;
+        break;
+    case PO_FILL:
+        m_value.ident = CSSValueFill;
+        break;
+    case PO_STROKE:
+        m_value.ident = CSSValueStroke;
+        break;
+    case PO_MARKERS:
+        m_value.ident = CSSValueMarkers;
+        break;
+    default:
+        ASSERT_NOT_REACHED();
+        m_value.ident = CSSValueNormal;
+        break;
+    }
+}
+
+template<> inline CSSPrimitiveValue::operator EPaintOrder() const
+{
+    switch (m_value.ident) {
+    case CSSValueNormal:
+        return PO_NORMAL;
+    case CSSValueFill:
+        return PO_FILL;
+    case CSSValueStroke:
+        return PO_STROKE;
+    case CSSValueMarkers:
+        return PO_MARKERS;
+    }
+
+    ASSERT_NOT_REACHED();
+    return PO_NORMAL;
+}
+
 template<> inline CSSPrimitiveValue::CSSPrimitiveValue(EMaskType e)
     : CSSValue(PrimitiveClass)
 {