anchor.diff:      debugEvent("NoInitializers");
       assert(ignore);
     }
  +
     void handleNoType(Token token) {
       debugEvent("NoType");
       if (ignore) return;
  
positive.code:     push(new Opaque(hint: "call"));
    }
  }
  /// A listener of parser events that builds summary information as parsing
  /// progresses.
  class SummaryBuilder extends StackListener {
  
negative.code:     pop();
      push(NullValue.Arguments);
    }
  
    void handleNewExpression(Token token) {
      debugEvent("NewExpression");
      if (ignore) return;
  