Travis doesn't need to manually upgrade HHVM in builds

.travis.yml

@@ -17,7 +17,6 @@ env:
   - DB=mysqli
 
 before_script:
-  - sh -c "if [ '$TRAVIS_PHP_VERSION' = 'hhvm' ]; then sudo apt-get remove --auto-remove hhvm; sudo apt-get update; sudo apt-get install -y --force-yes hhvm-nightly; fi"
   - sh -c "if [ '$DB' = 'pgsql' ]; then psql -c 'DROP DATABASE IF EXISTS doctrine_tests;' -U postgres; fi"
   - sh -c "if [ '$DB' = 'pgsql' ]; then psql -c 'DROP DATABASE IF EXISTS doctrine_tests_tmp;' -U postgres; fi"
   - sh -c "if [ '$DB' = 'pgsql' ]; then psql -c 'create database doctrine_tests;' -U postgres; fi"