anchor.diff:  /// enclosing label.
   class Label {
     final LabeledStatement statement;
  -  final StatementConfiguration configuration;
  +  final ExecConfiguration configuration;
     final Label enclosingLabel;
   
     Label(this.statement, this.configuration, this.enclosingLabel);
  
positive.code:   Configuration visitIfStatement(IfStatement node, State state) {
      var cont = new IfConditionContinuation(node.then, node.otherwise, state);
  
      return new ExpressionConfiguration(node.condition, state.environment, cont);
    }
  
    Configuration visitLabeledStatement(LabeledStatement node, State state) {
      return new StatementConfiguration(node.body, state.withBreak(node));
    }
  
    Configuration visitBreakStatement(BreakStatement node, State state) {
  
negative.code: class RedirectingConstructorApplication extends ApplicationContinuation {
    final Constructor constructor;
    final Environment environment;
    final ExecConfiguration configuration;
  
    RedirectingConstructorApplication(
        this.constructor, this.environment, this.configuration);
  