Revert "bug #18908 [DependencyInjection] force enabling the external XML entity loaders (xabbuh)"

This reverts commit 44f6f893083831ce9845c7d27c5e2cc855e0100b, reversing
changes made to 57d6053822866a56be7d7ea1db61a69390dcc528.

Author: nicolas-grekas

Loader/XmlFileLoader.php

@@ -333,9 +333,7 @@ public function validateSchema(\DOMDocument $dom)
 EOF
         ;
 
-        $disableEntities = libxml_disable_entity_loader(false);
         $valid = @$dom->schemaValidateSource($source);
-        libxml_disable_entity_loader($disableEntities);
 
         foreach ($tmpfiles as $tmpfile) {
             @unlink($tmpfile);

Tests/Loader/XmlFileLoaderTest.php

@@ -83,19 +83,6 @@ public function testParseFile()
         $this->assertInstanceOf('Symfony\\Component\\DependencyInjection\\SimpleXMLElement', $xml, '->parseFile() returns an SimpleXMLElement object');
     }
 
-    public function testLoaderTurnsOnEntityLoaderIfNecessary()
-    {
-        $oldValue = libxml_disable_entity_loader(true);
-
-        $containerBuilder = new ContainerBuilder();
-        $loader = new XmlFileLoader($containerBuilder, new FileLocator(self::$fixturesPath.'/xml'));
-        $loader->load('services2.xml');
-
-        libxml_disable_entity_loader($oldValue);
-
-        $this->assertTrue(count($containerBuilder->getParameterBag()->all()) > 0, 'Parameters can be read from the config file.');
-    }
-
     public function testLoadParameters()
     {
         $container = new ContainerBuilder();