extensions/emmet/src/editPoint.ts/findEditPoint
function findEditPoint(lineNum: number, editor: vscode.TextEditor, position: vscode.Position, direction: string): vscode.Selection | undefined {
	const line = editor.document.lineAt(lineNum);
	let lineContent = line.text;

	if (lineNum !== position.line && line.isEmptyOrWhitespace && lineContent.length) {
		return new vscode.Selection(lineNum, lineContent.length, lineNum, lineContent.length);
	}

	if (lineNum === position.line && direction === 'prev') {
		lineContent = lineContent.substr(0, position.character);
	}
	const emptyAttrIndex = direction === 'next' ? lineContent.indexOf('""', lineNum === position.line ? position.character : 0) : lineContent.lastIndexOf('""');
	const emptyTagIndex = direction === 'next' ? lineContent.indexOf('><', lineNum === position.line ? position.character : 0) : lineContent.lastIndexOf('><');

	let winner = -1;

	if (emptyAttrIndex > -1 && emptyTagIndex > -1) {
		winner = direction === 'next' ? Math.min(emptyAttrIndex, emptyTagIndex) : Math.max(emptyAttrIndex, emptyTagIndex);
	} else if (emptyAttrIndex > -1) {
		winner = emptyAttrIndex;
	} else {
		winner = emptyTagIndex;
	}

	if (winner > -1) {
		return new vscode.Selection(lineNum, winner + 1, lineNum, winner + 1);
	}
	return;
}