minor #21492 [DI] Deduplicate resources while adding them (nicolas-gr…

…ekas)

This PR was merged into the 3.3-dev branch.

Discussion
----------

[DI] Deduplicate resources while adding them

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

Since the string cast of resources is already used to deduplicate them, let's do it earlier. This can only decrease memory usage.

Commits
-------

04853fc [DI] Deduplicate resource while adding them

src/Symfony/Component/DependencyInjection/ContainerBuilder.php

@@ -202,7 +202,7 @@ public function hasExtension($name)
      */
     public function getResources()
     {
-        return array_unique($this->resources);
+        return array_values($this->resources);
     }
 
     /**
@@ -218,7 +218,7 @@ public function addResource(ResourceInterface $resource)
             return $this;
         }
 
-        $this->resources[] = $resource;
+        $this->resources[(string) $resource] = $resource;
 
         return $this;
     }