Fix for invalid 'extends/implements/with SomeEnum'.

pkg/analyzer/lib/src/dart/element/builder.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library analyzer.src.dart.element.builder;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
@@ skipping 138 matching lines @@
       element.external = true;
     }
     if (node.factoryKeyword != null) {
       element.factory = true;
     }
     element.functions = holder.functions;
     element.labels = holder.labels;
     element.localVariables = holder.localVariables;
     element.parameters = holder.parameters;
     element.isConst = node.constKeyword != null;
+    element.isCycleFree = element.isConst;
     if (body.isAsynchronous) {
       element.asynchronous = true;
     }
     if (body.isGenerator) {
       element.generator = true;
     }
     _currentHolder.addConstructor(element);
     node.element = element;
     if (constructorName == null) {
       Identifier returnType = node.returnType;
@@ skipping 1456 matching lines @@
     return null;
   }
 
   /**
    * Return the lexical identifiers associated with the given [identifiers].
    */
   static List<String> _getIdentifiers(NodeList<SimpleIdentifier> identifiers) {
     return identifiers.map((identifier) => identifier.name).toList();
   }
 }