extensions/emmet/src/util.ts/setupCdataNodeSubtree
export function setupCdataNodeSubtree(documentText: string, cdataNode: HtmlFlatNode): string {
	// blank out the rest of the document and generate the subtree.
	const cdataStart = '<![CDATA[';
	const cdataEnd = ']]>';
	const startToUse = cdataNode.start + cdataStart.length;
	const endToUse = cdataNode.end - cdataEnd.length;
	const beforePadding = ' '.repeat(startToUse);
	const cdataBody = beforePadding + documentText.substring(startToUse, endToUse);
	const innerRoot: HtmlFlatNode = parse(cdataBody);
	innerRoot.children.forEach(child => {
		cdataNode.children.push(child);
		child.parent = cdataNode;
	});
	return cdataBody;
}