support web-workers XMLHttpRequest

[hankhero]

for a web-worker, window is unavailable butXMLHttpRequest is available on the global 'self' object

[canastro]

This would be really useful!

[tschaub]

Agreed this would be useful. For others looking to work around the window checking, you can add this hack to whatever module requires http:

self.window = self;

And with this, window.XMLHttpRequest will be defined.