Description:
------------
In case the $domain argument has a value of 68+ characters long the function silently returns (bool) false and doesn't indicate an exceptional case.

Test script:
---------------
error_reporting(E_ALL);
ini_set('display_errors', 'on');

foreach ([67, 68] as $i) {
    $err = 0;

    $domain = str_pad('.com', $i, 'a', STR_PAD_LEFT);
    $asciiDomain = idn_to_ascii($domain, $err);

    if (false === $asciiDomain) {
        echo "Length limit is $i. Error '$err'. Stop.\n";
        var_dump($err);
    } else {
        echo "Length $i. asciiDomain is '$asciiDomain'. OK\n";
    }
}


Expected result:
----------------
PHP should at least report a warning about wrong input.

Actual result:
--------------
The function just returns (bool) false without any error indication.