Backport type fixes

Author: nicolas-grekas

Core/Validator/Constraints/UserPasswordValidator.php

@@ -45,6 +45,10 @@ public function validate($password, Constraint $constraint)
             return;
         }
 
+        if (!\is_string($password)) {
+            throw new UnexpectedTypeException($password, 'string');
+        }
+
         $user = $this->tokenStorage->getToken()->getUser();
 
         if (!$user instanceof UserInterface) {

Http/Firewall/ContextListener.php

@@ -328,7 +328,7 @@ private function safelyUnserialize(string $serializedToken)
     /**
      * @internal
      */
-    public static function handleUnserializeCallback($class)
+    public static function handleUnserializeCallback(string $class)
     {
         throw new \ErrorException('Class not found: '.$class, 0x37313bc);
     }