[SecurityBundle] removed the option to declare access_control rules based on request attributes

src/Symfony/Bundle/SecurityBundle/DependencyInjection/Configuration.php

@@ -107,16 +107,6 @@ class Configuration
                         ->beforeNormalization()->ifString()->then(function($v) { return preg_split('/\s*,\s*/', $v); })->end()
                         ->prototype('scalar')->end()
                     ->end()
-                    ->fixXmlConfig('attribute')
-                    ->arrayNode('attributes')
-                        ->useAttributeAsKey('key')
-                        ->prototype('scalar')
-                            ->beforeNormalization()
-                                ->ifTrue(function($v) { return is_array($v) && isset($v['pattern']); })
-                                ->then(function($v) { return $v['pattern']; })
-                            ->end()
-                        ->end()
-                    ->end()
                 ->end()
             ->end()
         ;