Description:
------------
In PHP versions < 5.3.0, one could specify INI option keys using non-ASCII characters; parse_ini_file would find these without issue.

Starting with 5.3.0, such options are silently dropped from the returned array of key/value pairs. The same is true of parse_ini_string().

I have the following extensions enabled:
bz2 Core ctype curl date dom ereg fileinfo filter gd gettext hash iconv intl json libxml mhash mysql openssl pcntl pcre PDO pdo_mysql pdo_sqlite Phar posix Reflection session SimpleXML soap sockets SPL SQLite sqlite3 standard tidy tokenizer xml xmlreader xmlwriter zip zlib

My php.ini is php.ini-development, with the only changes being to set my include_path and date.timezone.

Reproduce code:
---------------
$string =<<<EOT
Cooking_furniture="Küchen Möbel (en)"
Küchen_Möbel="Cooking furniture (en)"
EOT;

$data = parse_ini_string($string);
var_export($data);

Expected result:
----------------
array (
  'Cooking_furniture' => 'Küchen Möbel (en)',
  'Küchen_Möbel' => 'Cooking furniture (en)',
)

Actual result:
--------------
array (
  'Cooking_furniture' => 'Küchen Möbel (en)',
)