Charset encoding in Web Inspector

[Dmity-Sh]

Hello,

I've got a problem - Web Inspector shows data for Network -> Headers
in UTF-8 encoding.
It should show raw HTTP-headers information in ISO 8859-1 (Latin1)
encoding.
Even if I switch between "view parsed"/"view source" it is still in
UTF-8.

I have to use another tool to debug HTTP-headers (FF), because the
output is not actually the same as displayed.

How to check:

<?php
/* Save file in ISO 8859-1, 67 bytes length */
header( 'X-UTF-8: ГјtЖ’-8');
?>