Shorten null coalescing operator (#549)

Author: peter279k

src/BrowserFactory.php

@@ -65,7 +65,7 @@ public function __construct(string $chromeBinary = null)
      */
     public function createBrowser(?array $options = null): ProcessAwareBrowser
     {
-        $options = $options ?? $this->options;
+        $options ??= $this->options;
 
         // create logger from options
         $logger = self::createLogger($options);

src/Communication/ResponseReader.php

@@ -109,7 +109,7 @@ public function waitForResponse(int $timeout = null): Response
             return $this->getResponse();
         }
 
-        $timeout = $timeout ?? $this->connection->getSendSyncDefaultTimeout();
+        $timeout ??= $this->connection->getSendSyncDefaultTimeout();
 
         return Utils::tryWithTimeout($timeout * 1000, $this->waitForResponseGenerator());
     }