Fix a minor parameter issue

Summary: D1595 split encodeJSONForHTTPResponse() into two methods, but left a
straggling $use_javelin_shield parameter which is no longer used.

Test Plan: Caught errors in error log.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran, epriestley

Differential Revision: https://secure.phabricator.com/D1663

src/aphront/response/base/AphrontResponse.php

@@ -70,9 +70,7 @@ abstract class AphrontResponse {
     return $this;
   }
 
-  protected function encodeJSONForHTTPResponse(
-    array $object,
-    $use_javelin_shield) {
+  protected function encodeJSONForHTTPResponse(array $object) {
 
     $response = json_encode($object);