extensions/emmet/src/updateTag.ts/getRangesToUpdate
function getRangesToUpdate(document: vscode.TextDocument, selection: vscode.Selection, rootNode: HtmlFlatNode): TagRange[] {
	const documentText = document.getText();
	const offset = document.offsetAt(selection.start);
	const nodeToUpdate = getHtmlFlatNode(documentText, rootNode, offset, true);
	if (!nodeToUpdate) {
		return [];
	}
	return getRangesFromNode(nodeToUpdate, document);
}