minor symfony#22663 [DI] Fix PhpDumper blank lines around namespace (ogizanagi)

This PR was merged into the 2.7 branch.

Discussion
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[DI] Fix PhpDumper blank lines around namespace

| Q             | A
| ------------- | ---
| Branch?       | 2.7
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | N/A
| License       | MIT
| Doc PR        | N/A

symfony@219bce9 tries to fix CS in an expected PhpDumper output, which actually shows the PhpDumper does not create proper blank lines around the namespace.
That's why tests are failing on symfony#22660.

Commits
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c9f6c16 [DI] Fix PhpDumper blank lines around namespace

Author: fabpot

src/Symfony/Component/DependencyInjection/Dumper/PhpDumper.php

@@ -827,7 +827,7 @@ private function addNewInstance($id, Definition $definition, $return, $instantia
     private function startClass($class, $baseClass, $namespace)
     {
         $bagClass = $this->container->isFrozen() ? 'use Symfony\Component\DependencyInjection\ParameterBag\FrozenParameterBag;' : 'use Symfony\Component\DependencyInjection\ParameterBag\\ParameterBag;';
-        $namespaceLine = $namespace ? "namespace $namespace;\n" : '';
+        $namespaceLine = $namespace ? "\nnamespace $namespace;\n" : '';
 
         return <<<EOF
 <?php