Because redirects are atomic, we cannot dispatch loadend events and such on the XMLHttpRequestUpload class.
This effectively means that the moment we know we are not going to follow a redirect, we know we "completed" uploading (potentially several times). >From what I observed in Safari/Chrome it seems a separate task is what we want. This means e.g. a setTimeout() callback can run between loadend for upload and state switching to HEADERS_RECEIVED. Firefox also reports state as OPENED, though the setTimeout() callback runs much later (maybe due to a lower limit). http://dump.testsuite.org/xhr/upload-events.html was my test. Let me know if you have any concerns. This change will mostly be done in Fetch as that queues the networking tasks these days. -- http://annevankesteren.nl/
