[CompatAssetsBundle] Add missing namespace

src/Symfony/Bundle/CompatAssetsBundle/CompatAssetsBundle.php

@@ -2,6 +2,8 @@
 
 namespace Symfony\Bundle\CompatAssetsBundle;
 
+use Symfony\Component\HttpKernel\Bundle\Bundle;
+
 /*
  * This file is part of the Symfony framework.
  *