tests: migrate travis to xenial for modern Chrome support (#9654)

.travis.yml

@@ -8,24 +8,23 @@ matrix:
     - node_js: "10"
     - node_js: "12"
       if: head_branch IS blank AND branch = master
-dist: trusty
 cache:
   yarn: true
   directories:
     - node_modules
     - lantern-data
     - /home/travis/.rvm/gems/
 install:
+  # Ensure we have the latest Chrome stable.
+  - google-chrome-stable --version
   # if our e2e tests fail in the future it might be that we are not compatible
   # with the latest puppeteer api so we probably need to run on chromimum
   # @see https://github.com/GoogleChrome/lighthouse/pull/4640/files#r171425004
   - export PUPPETEER_SKIP_CHROMIUM_DOWNLOAD=1
   - yarn --frozen-lockfile
 before_script:
-  - export DISPLAY=:99.0
   # see comment above about puppeteer
   - export CHROME_PATH="$(which google-chrome-stable)"
-  - sh -e /etc/init.d/xvfb start
   # Print out the Chrome version so we know what we're working with
   - google-chrome-stable --version
   - yarn build-all
@@ -48,3 +47,5 @@ after_success:
   - yarn codecov
 addons:
   chrome: stable
+services:
+  - xvfb