platform/video.videojs/dist/video.es.js
function appendContent(el, content) {
  normalizeContent(content).forEach(function (node) {
    return el.appendChild(node);
  });
  return el;
}
function appendContent(el, content) {
  normalizeContent(content).forEach(function (node) {
    return el.appendChild(node);
  });
  return el;
}
Normalizes and appends content to an element.

@param {Element} el
Element to append normalized content to.


@param {String|Element|TextNode|Array|Function} content
See the `content` argument of {@link dom:normalizeContent}

@return {Element}
The element with appended normalized content.