Don't panic on https #2104
auto merge of #2166 : campadrenalin/servo/https-dont-panic, r=jdm

This is a stab at #2401 - I think this was what @jdm had in mind for a fix.

I've also included a test. There's no "i tried" star, I'm too much of a newb for that, but hopefully the test at least confirms that servo doesn't crash on HTTPS requests.