Move xvfb startup to script section

.travis.yml

@@ -21,8 +21,6 @@ branches:
 
 before_install:
   - nvm install 7
-  - export DISPLAY=:99.0
-  - sh -e /etc/init.d/xvfb start
   - OLD_VERSION=`mvn help:evaluate -Dexpression=project.version 2>/dev/null | grep -Ev "(^\[|Download\w+:)"`
   - NEW_VERSION=${OLD_VERSION%-SNAPSHOT}-dev-`printf %d $TRAVIS_BUILD_NUMBER`
   - echo "Building version $NEW_VERSION"
@@ -40,6 +38,9 @@ script:
   - mvn -e test -P \!htmlUnit
   - BASE_PATH=`pwd`
   - pushd tests/src/test/js
+  - export DISPLAY=:99.0
+  - sh -e /etc/init.d/xvfb start
+  - sleep 3
   - firefox index.html &
   - FIREFOX_PID=$!
   - node start.js $BASE_PATH/tests/target/js-tests