Travis builds are [broken](https://travis-ci.org/flutter/flutter/builds/246067983) due to the setup step failing [when we try to download the Google Cloud SDK](https://github.com/flutter/flutter/blob/be99a04dacc2ac77b445aff54df225c4cf951076/dev/bots/travis_setup.sh#L10).