Function fill

lib/css/syntax.js:598–603

(out, type, start, end)

 * @returns {MutableToken} `out`
 */
const fill = (out, type, start, end) => {
	out.type = type;
	out.start = start;
	out.end = end;
	return out;
};

/**
 * Whitespace token. Caller advances past the leading code point so