fix(ci): fix xvfb service issue

Author: Domainv

.travis.yml

@@ -1,11 +1,13 @@
 language: node_js
 node_js:
-  - "6"
+  - "10"
+
+services:
+  - xvfb
 
 before_install:
   - export CHROME_BIN=chromium-browser
   - export DISPLAY=:99.0
-  - sh -e /etc/init.d/xvfb start
 
 script:
   - npm run pretest