Merge branch '2.3' into 2.4

* 2.3:
  Fixed typo
  [validator] throw an exception if isn't an instance of ConstraintValidatorInterface.
  Reset the box model to content-box in the web debug toolbar
  [FrameworkBundle] Allowed "0" as a checkbox value in the php template.
  raising delta on stopwatch as travis really breaks with less than 35
  Switched to correct gender of "Token"
  fixed typos in several translations
  [HttpKernel] use static late binding when dumping out container

Author: fabpot

Kernel.php

@@ -712,7 +712,7 @@ protected function dumpContainer(ConfigCache $cache, ContainerBuilder $container
 
         $content = $dumper->dump(array('class' => $class, 'base_class' => $baseClass));
         if (!$this->debug) {
-            $content = self::stripComments($content);
+            $content = static::stripComments($content);
         }
 
         $cache->write($content, $container->getResources());