Description:
------------
wddx_serialize_value does not deal as expected with unicode characters in PHP 5.2.x or PHP 5.3.x. The function worked differently in PHP 5.1.6.

When serializing a string or a more complex objects any unicode characters get again utf8 encoded - instead of getting in as is.


Reproduce code:
---------------
<a href="?utf8=%E9%A1%B5">Demo</a> (some chinese character)
<hr>
<form method="get" action="?">
<input type="text" name="utf8">
<input type="submit">
</form>
<hr>
<?php 
if (isset($_GET["utf8"])) {
    echo $_GET["utf8"]."<br>"; 
    echo utf8_encode($_GET["utf8"])."<br>"; 
    echo wddx_serialize_value($_GET["utf8"])."<br>";
}    
?>

Expected result:
----------------
The demo code is a little script that outputs the given query parameter "utf8" in three way:

1. Directly as recieved
2. utf8_encoded
3. serialized via wddx_serialize_value

In <= 5.1.6 the resulting WDDX contained the utf8 characters excatly as given. In >= 5.2.0 the string gets UTF8 encoded again, just as if you would have valled utf8_encode on it.



Actual result:
--------------
While the new behavior might make sense for data going forward (although i am not sure what the expected behavior by WDDX spec is) this breaks backward compatibility with old data.

As we have millons of database rows in unicode WDDX data this is a huge issue (at least to us).

Can you please clarify if this is a bug, the expected behavior going forward and how to deal with backward compatibility issues (maybe an additional parameter to control the behavior)?

This might be related to bug #41722