Skip test on HHVM

- As there's no way to make that condition fail on that platform.

Author: weierophinney

test/Response/JsonResponseTest.php

@@ -92,6 +92,10 @@ public function testJsonErrorHandlingOfBadEmbeddedData()
             $this->markTestSkipped('Skipped as PHP versions prior to 5.5 are noisy about JSON errors');
         }
 
+        if (defined('HHVM_VERSION')) {
+            $this->markTestSkipped('Skipped as HHVM happily serializes embedded resources');
+        }
+
         // Serializing something that is not serializable.
         $data = [
             'stream' => fopen('php://memory', 'r'),