merged branch franmomu/reuse_variable_formpass (PR symfony#7464)

This PR was merged into the 2.1 branch.

Discussion
----------

[FrameworkBundle] Reuse definition variable in FormPass

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

Commits
-------

f52320d [FrameworkBundle] Reuse definition variable in FormPass

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

@@ -28,6 +28,8 @@ public function process(ContainerBuilder $container)
             return;
         }
 
+        $definition = $container->getDefinition('form.extension');
+
         // Builds an array with service IDs as keys and tag aliases as values
         $types = array();
 
@@ -40,7 +42,7 @@ public function process(ContainerBuilder $container)
             $types[$alias] = $serviceId;
         }
 
-        $container->getDefinition('form.extension')->replaceArgument(1, $types);
+        $definition->replaceArgument(1, $types);
 
         $typeExtensions = array();
 
@@ -52,11 +54,11 @@ public function process(ContainerBuilder $container)
             $typeExtensions[$alias][] = $serviceId;
         }
 
-        $container->getDefinition('form.extension')->replaceArgument(2, $typeExtensions);
+        $definition->replaceArgument(2, $typeExtensions);
 
         // Find all services annotated with "form.type_guesser"
         $guessers = array_keys($container->findTaggedServiceIds('form.type_guesser'));
 
-        $container->getDefinition('form.extension')->replaceArgument(3, $guessers);
+        $definition->replaceArgument(3, $guessers);
     }
 }