LearnBoost/engine.io-client — pull request #217 by 3rd-Eden (2013-12-16 19:57:45+00:00)
Title: Completely remove the use of XDomainRequest

1. It doesn't work from HTTP to HTTPS connections
2. It does not send Cookie headers, no auth headers, no nothing to authenticate the connection.

See http://blogs.msdn.com/b/ieinternals/archive/2010/05/13/xdomainrequest-restrictions-limitations-and-workarounds.aspx