FileRequest: identify unknown files.

* WebKit testsuite relies on the MIME types being correct, so when the
file doesn't have one, try to identify it.
* May be useful for other apps using FileRequest, anyway.

src/kits/network/libnetapi/FileRequest.cpp

@@ -59,6 +59,8 @@ BFileRequest::_ProtocolLoop()
 
 		BNodeInfo info(&file);
 		char mimeType[B_MIME_TYPE_LENGTH + 1];
+		if (info.GetType(mimeType) != B_OK)
+			update_mime_info(fUrl.Path().String(), false, true, false);
 		if (info.GetType(mimeType) == B_OK)
 			fResult.SetContentType(mimeType);