Add matrix to Travis

Adding `matrix` to travis testing will allow Travis to parallel test
different builds in separate processes.
Use matrix for browser/build testing
Removing IE6 because it hangs up on Travis/Sauce
Removing sniffing in the test
Merge remote-tracking branch 'kentaromiura/fix-breaking-test'
Merge remote-tracking branch 'sergio/JSONdecode'
Merge remote-tracking branch 'sergio/matrix'
Use Element.matches if available

Spec:
http://dom.spec.whatwg.org/#dom-element-matches

Support in Chromium:
https://code.google.com/p/chromium/issues/detail?id=326652

Element.matchesSelector was never standardized and it is not available
in the most recent versions of Blink, Gecko, Presto, Trident or WebKit.