[FrameworkBundle] simplified some code

src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Compiler/AddConstraintValidatorsPass.php

@@ -29,9 +29,6 @@ class AddConstraintValidatorsPass implements CompilerPassInterface
             }
         }
 
-        $definition = $container->getDefinition('validator.validator_factory');
-        $arguments = $definition->getArguments();
-        $arguments[1] = $validators;
-        $definition->setArguments($arguments);
+        $container->getDefinition('validator.validator_factory')->setArgument(1, $validators);
     }
 }

src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Compiler/AddFieldFactoryGuessersPass.php

@@ -33,9 +33,6 @@ class AddFieldFactoryGuessersPass implements CompilerPassInterface
             return new Reference($id);
         }, array_keys($container->findTaggedServiceIds('form.field_factory.guesser')));
 
-        $definition = $container->getDefinition('form.field_factory');
-        $arguments = $definition->getArguments();
-        $arguments[0] = $guessers;
-        $definition->setArguments($arguments);
+        $container->getDefinition('form.field_factory')->setArgument(0, $guessers);
     }
 }

src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Compiler/AddSecurityVotersPass.php

@@ -35,9 +35,6 @@ class AddSecurityVotersPass implements CompilerPassInterface
             return new Reference($id);
         }, array_keys($container->findTaggedServiceIds('security.voter')));
 
-        $definition = $container->getDefinition('security.access.decision_manager');
-        $arguments = $definition->getArguments();
-        $arguments[0] = $voters;
-        $definition->setArguments($arguments);
+        $container->getDefinition('security.access.decision_manager')->setArgument(0, $voters);
     }
 }