Disable forwarding of progress events

Temporarily disable binding to progress events of
XMLHttpRequestUpload objects.

This results in no progress bar on photo uploads but enables uploads to
Commons using CORS.

This commit should be reverted when
https://bugzilla.wikimedia.org/show_bug.cgi?id=44921 is resolved.

Change-Id: I4d300ebbc2768ee807f6692d05e7815bb62aba85