The XHR spec currently allows users to set the "Proxy-Connection" header
using setRequestHeader method. I couldn't find a spec for it other than
some discussions here:
http://www.hpl.hp.com/personal/ange/archives/http-wg-archive/index.html#1214
However it seems like it basically does the same thing for a
client-proxy connection as the normal "Connection" header does for a
client-server connection.
Mozilla seems to set the "Proxy-Connection" header rather than
"Connection" when knowingly talking to a proxy. See
http://bonsai.mozilla.org/cvsblame.cgi?file=mozilla/netwerk/protocol/http/src/nsHttpHandler.cpp&rev=1.129#387
(warning, licensed code, talk to your lawyer ;) )
So I think we should disallow this header since we're disallowing
"Connection" as it might otherwise confuse proxies.
Best Regards,
Jonas
