Use dev-master version of htmlpurifier in HHVM tests on Travis CI (#24)

Author: xemlock

.travis.yml

@@ -24,6 +24,9 @@ before_install:
 
 install:
     - composer install
+    # Last released version of htmlpurifier (4.10.0) is broken on HHVM
+    # https://github.com/ezyang/htmlpurifier/issues/169
+    - if [ "${TRAVIS_PHP_VERSION}" == "hhvm" ]; then composer require 'ezyang/htmlpurifier:dev-master#89b3fe4'; fi
 
 script:
     - mkdir -p build/logs