Cleaning up Travis config

.travis.yml

@@ -3,17 +3,10 @@ dist: trusty
 language: node_js
 node_js:
   - "8"
-env:
-  - PHANTOMJS_VERSION="2.1.1" PATH="$PWD/travis_phantomjs/phantomjs-$PHANTOMJS_VERSION-linux-x86_64/bin:$PATH"
-cache:
-  directories:
-    - travis_phantomjs
 notifications:
   email: false
 before_install:
   - export CHROME_BIN=chromium-browser
-  - export DISPLAY=:99.0
-  - sh -e /etc/init.d/xvfb start
 install:
   # Disable the spinner; it looks bad on Travis.
   - npm config set spin false