chore: switch to headless Chrome/Firefox and simplify/improve Travis config

Author: gkalpak

.travis.yml

@@ -1,18 +1,17 @@
-sudo: required
 dist: trusty
 
 language: node_js
 node_js:
   - 6  # Because `[email protected]` requires 6.9+.
   - 10
 
-before_script:
-  - export DISPLAY=:99.0
-  - sh -e /etc/init.d/xvfb start
-  - wget -q -O - https://dl-ssl.google.com/linux/linux_signing_key.pub | sudo apt-key add -
-  - sudo sh -c 'echo "deb [arch=amd64] http://dl.google.com/linux/chrome/deb/ stable main" >> /etc/apt/sources.list.d/google-chrome.list'
-  - sudo apt-get update -q
-  - sudo apt-get install -q google-chrome-stable
+addons:
+  chrome: stable
+  firefox: latest
+
+cache:
+  directories:
+    - "$HOME/.npm"
 
 script:
   - scripts/private/test-all.sh

scripts/private/test-all.sh

@@ -38,6 +38,6 @@ do
     git checkout -f $COMMIT~$((14 - $i))
   fi
 
-  node_modules/.bin/karma start karma.conf.js --single-run
-  node_modules/.bin/protractor e2e-tests/protractor.conf.js --directConnect
+  node_modules/.bin/karma start karma.conf.js --single-run --browsers ChromeHeadless,FirefoxHeadless
+  node_modules/.bin/protractor e2e-tests/protractor.conf.js --directConnect --capabilities.chromeOptions.args headless
 done