var calc = {

  sumArray (items) {

    return items.reduce(function(a, b) {

      return a + b;

    });

  }

};

var numbers = {

  __proto__: calc,

  numbers: [4, 6, 7],

  sumElements: function() {

    return super.sumArray(this.numbers);

  }

};

// Throws SyntaxError: 'super' keyword unexpected here

numbers.sumElements();