minor #16349 [VarExporter] Make example work (antalaron)

This PR was merged into the 4.4 branch.

Discussion
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[VarExporter] Make example work

The exported php file is not a valid php as it does not contain the opening tag and has no `return` and closing semicolon. So the require won't work as expected.

Commits
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5832e22 Make example work

Author: javiereguiluz

components/var_exporter.rst

@@ -28,7 +28,7 @@ PHP code, similar to PHP's :phpfunction:`var_export` function::
 
     $exported = VarExporter::export($someVariable);
     // store the $exported data in some file or cache system for later reuse
-    $data = file_put_contents('exported.php', $exported);
+    $data = file_put_contents('exported.php', '<?php return '.$exported.';');
 
     // later, regenerate the original variable when you need it
     $regeneratedVariable = require 'exported.php';