public static boolean isQuotelessUrlFunction(ASTCssNode kid) {
if (kid.getType() != ASTCssNodeType.FUNCTION)
return false;
FunctionExpression function = (FunctionExpression) kid;
String name = function.getName();
if (!"url".equals(name == null ? null : name.toLowerCase()))
return false;
Expression parameter = function.getParameter().splitByComma().get(0);
if (parameter.getType()!=ASTCssNodeType.STRING_EXPRESSION)
return false;
CssString stringParameter = (CssString)parameter;
return "".equals(stringParameter.getQuoteType());