if (!parent || parent.nodeType !== 1 || !Handsontable.Dom.hasClass(parent, 'wtHolder')) {
    var hider = document.createElement('DIV');
    hider.className = 'wtHider';
    if (parent) {
      parent.insertBefore(hider, this.spreader); //if TABLE is detached (e.g. in Jasmine test), it has no parentNode so we cannot attach holder to it