code: function getStylesheetsOfRootNode(options) {
  	const { rootNode, shadowId } = options;
  	let sheets;
  
  	// nodeType === 11  -> DOCUMENT_FRAGMENT
  	if (rootNode.nodeType === 11 && shadowId) {
  		sheets = getStylesheetsFromDocumentFragment(options);
  	} else {
  		sheets = getStylesheetsFromDocument(rootNode);
  	}
  
  	return filterStylesheetsWithSameHref(sheets);
  }
docs: Get stylesheet(s) for root
  
  @param {Object} options configuration options of `loadCssom`
  @returns an array of stylesheets