bug #29992 [DependencyInjection] fix DOM element namespace URL access (xabbuh)

This PR was merged into the 4.3-dev branch.

Discussion
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[DependencyInjection] fix DOM element namespace URL access

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

Commits
-------

429bddf96b fix DOM element namespace URL access

src/Symfony/Component/DependencyInjection/Loader/XmlFileLoader.php

@@ -672,7 +672,7 @@ EOF
         }
 
         foreach ($alias->childNodes as $child) {
-            if (!$child instanceof \DOMElement && self::NS !== $child->namespaceURI) {
+            if (!$child instanceof \DOMElement || self::NS !== $child->namespaceURI) {
                 continue;
             }
             if (!\in_array($child->localName, ['deprecated'], true)) {