Don't run browser tests in PRs because they fail
Don't run browser tests in PRs because they fail

Travis has an issue where PRs can’t access Sauce Labs credentials.

See:
https://support.saucelabs.com/entries/25614798-How-can-we-set-up-an-open
-source-account-that-runs-tests-on-people-s-pull-requests-

feross/webtorrent-cli,feross/webtorrent-cli