Set default timezone in PHPUnit bootstrap to pass HHVM tests

tests/bootstrap.php

@@ -9,6 +9,11 @@ if (!file_exists(dirname(__DIR__) . '/vendor/autoload.php')) {
         . "See http://getcomposer.org for help with installing composer\n");
 }
 
+var_dump(phpversion());
+
+// Set a default timezone for HHVM tests
+date_default_timezone_set('UTC');
+
 // Include the Composer autoloader
 $loader = include realpath(dirname(__FILE__) . '/../vendor/autoload.php');