Issue 3968. Report error if cycle in redirecting factory constructors

compiler/java/com/google/dart/compiler/resolver/Elements.java

 // Copyright (c) 2012, 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.
 
 package com.google.dart.compiler.resolver;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Objects;
 import com.google.common.collect.Lists;
 import com.google.dart.compiler.DartSource;
@@ skipping 662 matching lines @@
   }
 
   /**
    * @return <code>true</code> if the given {@link ConstructorElement} is a default constructor.
    */
   public static boolean isDefaultConstructor(ConstructorElement element) {
     return element != null
         && element.getParameters().isEmpty()
         && getRawMethodName(element).equals(element.getEnclosingElement().getName());
   }
+  
+  public static void setRedirectingFactoryConstructor(ConstructorElement source,
+      ConstructorElement target) {
+    ((ConstructorElementImplementation) source).setRedirectingFactoryConstructor(target);
+  }
 
   /**
    * @return the name of given {@link DartNode} if it is {@link DartIdentifier}, or
    *         <code>null</code> otherwise.
    */
   private static String getIdentifierName(DartNode identifier) {
     if (identifier != null && identifier instanceof DartIdentifier) {
       return ((DartIdentifier) identifier).getName();
     }
     return null;
@@ skipping 118 matching lines @@
       return false;
     }
     Source source = member.getElement().getSourceInfo().getSource();
     return !isCoreLibrarySource(source);
   }
   
   public static DuplicateElement createDuplicateElement(Element oldElement, Element newElement) {
     return new DuplicateElementImplementation(oldElement, newElement);
   }
 }