Merge branch '5.1' into 5.2

* 5.1:
  CS: Apply ternary_to_null_coalescing fixer

Author: derrabus

DependencyInjection/RegisterListenersPass.php

@@ -83,7 +83,7 @@ public function process(ContainerBuilder $container)
             $noPreload = 0;
 
             foreach ($events as $event) {
-                $priority = isset($event['priority']) ? $event['priority'] : 0;
+                $priority = $event['priority'] ?? 0;
 
                 if (!isset($event['event'])) {
                     if ($container->getDefinition($id)->hasTag($this->subscriberTag)) {

EventDispatcher.php

@@ -184,10 +184,10 @@ public function addSubscriber(EventSubscriberInterface $subscriber)
             if (\is_string($params)) {
                 $this->addListener($eventName, [$subscriber, $params]);
             } elseif (\is_string($params[0])) {
-                $this->addListener($eventName, [$subscriber, $params[0]], isset($params[1]) ? $params[1] : 0);
+                $this->addListener($eventName, [$subscriber, $params[0]], $params[1] ?? 0);
             } else {
                 foreach ($params as $listener) {
-                    $this->addListener($eventName, [$subscriber, $listener[0]], isset($listener[1]) ? $listener[1] : 0);
+                    $this->addListener($eventName, [$subscriber, $listener[0]], $listener[1] ?? 0);
                 }
             }
         }