Function boa::builtins::number::to_locale_string

pub fn to_locale_string(
    this: &Value, 
    _args: &[Value], 
    _ctx: &mut Interpreter
) -> ResultValue

Number().toLocaleString()

https://tc39.es/ecma262/#sec-number.prototype.tolocalestring

Note that while this technically conforms to the Ecma standard, it does no actual internationalization logic.