Unused local variable in testSerialization()

in /core/tests/Drupal/Tests/Core/DependencyInjection/DependencySerializationTest.php , I think I see an unused variable.

The code block is

    $string = serialize($dependencySerialization);
    $object = unserialize($string);

    $string = serialize($dependencySerialization);
    /** @var \Drupal\Tests\Core\DependencyInjection\DependencySerializationTestDummy $object */
    $dependencySerialization = unserialize($string);

    $this->assertSame($service, $dependencySerialization->service);
    $this->assertSame($container, $dependencySerialization->container);
    $this->assertEmpty($dependencySerialization->getServiceIds());

Here you can see that $object is defined but never used. Futhermore the same operatation unserialize($string) is stored into $dependencySerialization so it's also redundant. Which makes the typing above $dependencySerialization weird. Oh I just noticed that $string is reset too. So I guess this can be removed:

    $string = serialize($dependencySerialization);
    $object = unserialize($string);

and we should fix the object typing.