bug #37020 [ExpressionLanguage] reset the internal state when the parser is finished (xabbuh)

This PR was merged into the 5.1 branch.

Discussion
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[ExpressionLanguage] reset the internal state when the parser is finished

| Q             | A
| ------------- | ---
| Branch?       | 5.1
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Tickets       |
| License       | MIT
| Doc PR        |

Commits
-------

d58eb020d0 reset the internal state when the parser is finished

src/Symfony/Component/ExpressionLanguage/Parser.php

@@ -124,6 +124,9 @@ class Parser
             throw new SyntaxError(sprintf('Unexpected token "%s" of value "%s".', $stream->current->type, $stream->current->value), $stream->current->cursor, $stream->getExpression());
         }
 
+        $this->stream = null;
+        $this->names = null;
+
         return $node;
     }