Generate option elements for menu. Removes previously appended elements.
@memberof Menu
@instance
function createOptions() {
    this.element.innerHTML = '';

    var _iteratorNormalCompletion = true;
    var _didIteratorError = false;
    var _iteratorError = undefined;

    try {
      for (var _iterator = this.options[Symbol.iterator](), _step; !(_iteratorNormalCompletion = (_step = _iterator.next()).done); _iteratorNormalCompletion = true) {
        var option = _step.value;

        var optionEl = document.createElement('option');
        optionEl.setAttribute('value', option);
        optionEl.innerText = option;
        this.element.appendChild(optionEl);
      }
    } catch (err) {
      _didIteratorError = true;
      _iteratorError = err;
    } finally {
      try {
        if (!_iteratorNormalCompletion && _iterator.return) {
          _iterator.return();
        }
      } finally {
        if (_didIteratorError) {
          throw _iteratorError;
        }
      }
    }
  }