minor #23512 [DI] Remove unused dynamic property (dunglas)

This PR was merged into the 3.3 branch.

Discussion
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[DI] Remove unused dynamic property

| Q             | A
| ------------- | ---
| Branch?       | 3.3
| Bug fix?      | no
| New feature?  | no <!-- don't forget updating src/**/CHANGELOG.md files -->
| BC breaks?    | no
| Deprecations? | no <!-- don't forget updating UPGRADE-*.md files -->
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

Commits
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6de81a7756 [DI] Remove unused dynamic property

src/Symfony/Component/DependencyInjection/Dumper/PhpDumper.php

@@ -120,7 +120,6 @@ class PhpDumper extends Dumper
             'debug' => true,
         ), $options);
 
-        $this->classResources = array();
         $this->initializeMethodNamesMap($options['base_class']);
 
         $this->docStar = $options['debug'] ? '*' : '';