code: function getMarkupWrap(nodeName) {
    invariant(!!dummyNode, 'Markup wrapping node not initialized');
    if (!markupWrap.hasOwnProperty(nodeName)) {
      nodeName = '*';
    }
    if (!shouldWrap.hasOwnProperty(nodeName)) {
      if (nodeName === '*') {
        dummyNode.innerHTML = '<link />';
      } else {
        dummyNode.innerHTML = '<' + nodeName + '></' + nodeName + '>';
      }
      shouldWrap[nodeName] = !dummyNode.firstChild;
    }
    return shouldWrap[nodeName] ? markupWrap[nodeName] : null;
  }
docs: Gets the markup wrap configuration for the supplied `nodeName`.
  
  NOTE: This lazily detects which wraps are necessary for the current browser.
  
  @param {string} nodeName Lowercase `nodeName`.
  @return {?array} Markup wrap configuration, if applicable.