Start separating ClassElementImpl for Class and Enum.

pkg/analyzer/lib/src/context/context.dart

Index: pkg/analyzer/lib/src/context/context.dart
diff --git a/pkg/analyzer/lib/src/context/context.dart b/pkg/analyzer/lib/src/context/context.dart
index 23cae4a19f758d42274dfcd27ce07939dd07b9c8..29bc461d2ba51dfedd517b8cd5696374b29669f0 100644
--- a/pkg/analyzer/lib/src/context/context.dart
+++ b/pkg/analyzer/lib/src/context/context.dart
@@ -724,7 +724,7 @@ class AnalysisContextImpl implements InternalAnalysisContext {
 
     ClassElement _classElement(String typeName, [List<String> parameterNames]) {
       ClassElementImpl element =
-          new ClassElementImpl.forNode(AstFactory.identifier3(typeName));
+          new ClassElementImpl_Class.forNode(AstFactory.identifier3(typeName));
       element.supertype = objType;
       InterfaceTypeImpl type = new InterfaceTypeImpl(element);
       element.type = type;