[xhr] Sort headers lexicographically in getAllResponseHeaders and combine values too (#50)

In Fetch we changed this in whatwg/fetch#189 per a suggestion from @youennf. We should probably change it here too.

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Reply to this email directly or view it on GitHub:
https://github.com/whatwg/xhr/issues/50

Received on Thursday, 28 January 2016 15:55:01 UTC