code: function createOrientationModal (onClick) {
    var modal = document.createElement('div');
    modal.className = ORIENTATION_MODAL_CLASS;
    modal.classList.add(HIDDEN_CLASS);
    modal.setAttribute(constants.AFRAME_INJECTED, '');
  
    var exit = document.createElement('button');
    exit.setAttribute(constants.AFRAME_INJECTED, '');
    exit.innerHTML = 'Exit VR';
  
    // Exit VR on close.
    exit.addEventListener('click', onClick);
  
    modal.appendChild(exit);
  
    return modal;
  }
docs: Creates a modal dialog to request the user to switch to landscape orientation.
  
  @param {function} onClick - click event handler
  @returns {Element} Wrapper <div>.