Use Karma to run tests against browsers

[just-boris]

My second attempt to solve #2

I changed my mind and tried to do with karma. The result is nice, all test cases are passing, except IE.

[jeffcarp]

Hey @just-boris thanks again, I really appreciate your work on this. I took a first look but I'm still out of the country with limited internet. Here are 2 things I noticed:

1. I still think CI should fail if Sauce isn't configured. This prevents the situation where the Sauce credentials in Travis become misconfigured but we don't find out about it until later.
2. Is there a reason you chose Webpack vs. Browserify? I don't have a preference - just curious.

[just-boris]

1. For pull-requests build Sauce credentials is unavailable, so we need a fallback to test at least in one browser upcoming commits. Added a check to be sure that you have both SAUCE_USERNAME and SAUCE_ACCESS_KEY parameters. If you would have only one, you will get an error. Also, if you have wrong API key, Sauce rejects your test on remote endpoint and you will get a proper message.
2. I have more experience with webpack and I already have this setup in my another projects.

[just-boris]

What should I do to finish this?

[jeffcarp]

Hey Boris sorry I should have updated this thread too - I tried looking into the IE failures last night but didn't get super far. What do you think about merging this into master without IE and creating a separate issue for it?

[just-boris]

@jeffcarp done

[jeffcarp]

Awesome, merged! Thanks for all your work @just-boris!!

I'll work on getting the sauce credentials into Travis.

[jeffcarp]

Chrome and Firefox are now being tested in CI! https://travis-ci.org/jsdom/abab/builds/87237430

Thanks again for your PRs @just-boris, I really appreciate it!

[just-boris]

🎉