Fixed HHVM build

Author: Nyholm

.travis.yml

@@ -10,7 +10,7 @@ php:
     - 5.5
     - 5.6
     - 7.0
-    - hhvm
+    - 7.1
 
 env:
     global:
@@ -27,6 +27,8 @@ matrix:
     include:
         - php: 5.5
           env: COMPOSER_FLAGS="--prefer-stable --prefer-lowest" COVERAGE=true TEST_COMMAND="composer test-ci"
+        - php: hhvm
+          dist: trusty
 
 before_install:
     - if [[ $COVERAGE != true && $TRAVIS_PHP_VERSION != hhvm ]]; then phpenv config-rm xdebug.ini; fi