Investigate CI error

[Timer]

https://travis-ci.org/facebook/create-react-app/jobs/393662639#L2786-L2810

[omermindivanli]

Just googled the error, I think it is related to jsdom https://goo.gl/JH5DzE

[Brew-Brew]

I fixed this issue by version up jsdom in kitchensink dependecy :) I #4678

[bugzpodder]

I finally got two green builds in travis after separating out kitchensink tests into two tests #4767
I've seen a variety of error messages on Travis, and haven't had much success fixing all of them, but I think having two tests helps a lot, whereas before there were many timeouts from yarn build/request fetching.

current mocha tests: https://travis-ci.org/facebook/create-react-app/builds/403949036
experimental jest tests: https://travis-ci.org/facebook/create-react-app/builds/403952760