Stalled Travis Build

[Will Hill]

Description

.travis.yml

language: node_js
node_js:
  - "9"
  - "8"
dist: trusty
sudo: required
addons:
  chrome: stable
cache:
  directories:
    - node_modules
install:
  - npm install
before_script:
  - export DISPLAY=:99.0
  - npm run lint
script:
  - xvfb-run npm run test
  - xvfb-run npm run test:integration

Expected outcome

1-2 min build and test

Actual outcome

10min + build and test

Live Demo

https://travis-ci.org/bkawk/travis-s3/jobs/471082754

Steps to reproduce

1. Install the latest polymer starter kit
2. add .travis.yml

[Keanu Lee]

Not sure if it's related to your issue, but I was able to get Travis building and passing after refreshing package-lock.json and using Node 10 (https://travis-ci.org/Polymer/polymer-starter-kit/builds/471145166). Just merged these changes to the master branch in #1130.