_makeSelectOptionList(selectlist) {
    forEach(BLEND_OPTIONS, (option) => {
      const selectOption = document.createElement('option');
      selectOption.setAttribute('value', option);
      selectOption.innerHTML = option.replace(/^[a-z]/, ($0) => $0.toUpperCase());
      selectlist.appendChild(selectOption);
    });
  }
Make option list for select control
@param {HTMLElement} selectlist - blend option select list element
@private