Right now the Web Inspector does not show all of the Request Headers when fetching a Resource. I verified that it is at least sending the Accept-Language header (to my server) but that does not show up in the expando list for the "Request Headers" of that Resource. Firebug does show them, and this was actually the root of my problem.
Created attachment 28144 [details] Image of Inspector Only Showing 2 Headers... What about the others? Image of Inspector Only Showing 2 Headers... What about the others?
Without actually investigating these, here is a couple of guesses that may be relevant: - the missing headers are likely those added by NSURLConnection, which is why WebKit doesn't know about these; - it should be possible to store the actual request in connection:willSendRequest:redirectResponse: delegate call (see comment about <rdar://problem/5380697> there).
Closing as invalid, as this bug pertains to the old inspector UI and/or its tests. Please file a new bug (https://www.webkit.org/new-inspector-bug) if the bug/feature/issue is still relevant to WebKit trunk.