To reproduce: 1. run-webkit-tests fast/encoding/percent-escaping.html The test times out. See <http://build.webkit.org/results/Windows%20Release%20(Tests)/r43702%20(921)/fast/encoding/percent-escaping-pretty-diff.html> for the diff of the failure.
Preliminary investigation shows that CFNetwork is returning a MIME type of "application/octet-stream" for the <form>'s action attribute. On OS X it returns "text/html", which is far more sensible. Opening this test in Safari causes Safari to open Windows Explorer pointing the the <form>'s action attribute.
Added to the Skipped file in r43706
Seems like this might be a CFNetwork bug.
<rdar://problem/6887936>
Looks like this started failing after Brady's content-sniffing changes.
This now works properly.