merged branch hason/bc_xml (PR #6393)

This PR was submitted for the master branch but it was merged into the 2.2 branch instead (closes #6393).

Commits
-------

697d53d [Router] Fixed XmlFileLoaderTest::testLoadThrowsExceptionWithInvalidFileEvenWithoutSchemaValidation

Discussion
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[Router] Fixed test

src/Symfony/Component/Routing/Tests/Fixtures/CustomXmlFileLoader.php

@@ -12,14 +12,15 @@
 namespace Symfony\Component\Routing\Tests\Fixtures;
 
 use Symfony\Component\Routing\Loader\XmlFileLoader;
+use Symfony\Component\Config\Util\XmlUtils;
 
 /**
  * XmlFileLoader with schema validation turned off
  */
 class CustomXmlFileLoader extends XmlFileLoader
 {
-    protected function validate(\DOMDocument $dom)
+    protected function loadFile($file)
     {
-        return true;
+        return XmlUtils::loadFile($file, function() { return true; });
     }
 }