Merge branch '3.3' into 3.4

* 3.3:
  Fail as early and noisily as possible
  [FrameworkBundle] Fix visibility of a test helper
  [link] clear the cache after linking
  [link] Prevent warnings when running link with 2.7
  [Validator] ExpressionValidator should use OBJECT_TO_STRING to allow value in message
  do not eagerly filter comment lines
  [WebProfilerBundle], [TwigBundle] Fix Profiler breaking XHTML pages (Content-Type: application/xhtml+xml)

Author: nicolas-grekas

Tests/Controller/RedirectControllerTest.php

@@ -314,7 +314,7 @@ private function createLegacyRedirectController($httpPort = null, $httpsPort = n
         return $controller;
     }
 
-    public function assertRedirectUrl(Response $returnResponse, $expectedUrl)
+    private function assertRedirectUrl(Response $returnResponse, $expectedUrl)
     {
         $this->assertTrue($returnResponse->isRedirect($expectedUrl), "Expected: $expectedUrl\nGot:      ".$returnResponse->headers->get('Location'));
     }