Character encoding when using @JavaScript annotation

I have a few custom components, which extend AbstractJavaScriptComponent and include corresponding JavaScript files via @JavaScript annotation. The files get downloaded into the client, but Firefox shows an information, that character encoding is not set on them.
I also have problems while exchanging data between client and server where national characters were used by the user in input fields.
I think the latter might be related to the lack of character encoding setting on the SCRIPT tag - I hope it would be resolved if I could have the file loaded into SCRIPT element looking like this:

<script type="text/javascript" src="..." charset="utf-8"></script>

It it possible to achieve that?

Thank you in advance for any hints.