anchor.diff:        ConstructorElement constructor,
         ConstantVisitor constantVisitor,
         ErrorReporter errorReporter) {
  -    if (!_getConstructorBase(constructor).isCycleFree) {
  +    if (!_getConstructorImpl(constructor).isCycleFree) {
         // It's not safe to evaluate this constructor, so bail out.
         // TODO(paulberry): ensure that a reasonable error message is produced
         // in this case, as well as other cases involving constant expression
  
positive.code:   void computeDependencies(
        ConstantEvaluationTarget constant, ReferenceFinderCallback callback) {
      ReferenceFinder referenceFinder = new ReferenceFinder(callback);
      if (constant is VariableElementImpl) {
        Expression initializer = constant.constantInitializer;
        if (initializer != null) {
  
negative.code:       name.isEmpty ||
        name == "void" ||
        new JavaPatternMatcher(_PUBLIC_SYMBOL_PATTERN, name).matches();
  }
  
  /**
  