minor symfony#12907 Update extending.rst (atailouloute)

This PR was merged into the 4.3 branch.

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Update extending.rst

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0536c0a Update extending.rst

Author: javiereguiluz

Diff for: components/expression_language/extending.rst

@@ -125,12 +125,12 @@ or by using the second argument of the constructor::
 
         class ExpressionLanguage extends BaseExpressionLanguage
         {
-            public function __construct(CacheItemPoolInterface $parser = null, array $providers = [])
+            public function __construct(CacheItemPoolInterface $cache = null, array $providers = [])
             {
                 // prepends the default provider to let users override it
                 array_unshift($providers, new StringExpressionLanguageProvider());
 
-                parent::__construct($parser, $providers);
+                parent::__construct($cache, $providers);
             }
         }