Fixed HHVM tests compatibility

tests/framework/helpers/FormatConverterTest.php

@@ -81,7 +81,13 @@ class FormatConverterTest extends TestCase
                         break;
                 }
 
-                $this->assertEquals($expected, $fmt->getPattern(), "Format for $format $name does not match.");
+                $pattern = $fmt->getPattern();
+
+                if (defined('HHVM_VERSION') && $name === 'short') {
+                    $pattern = str_replace(',', ' ', $pattern); // Remove comma between date and time ('M/d/yy, h:mm a')
+                }
+
+                $this->assertEquals($expected, $pattern, "Format for $format $name does not match.");
             }
         }
     }