Typo when expression language is used to configure a service.

Typo in XML and PHP code block when expression language is used to configure a service.

```
  [Symfony\Component\ExpressionLanguage\SyntaxError]  
  Unexpected character "@" around position 0.       
```
bug #4564 Typo when expression language is used to configure a service. (rubenrua)

This PR was submitted for the 2.6 branch but it was merged into the 2.5 branch instead (closes #4564).

Discussion
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Typo when expression language is used to configure a service.

Typo in XML and PHP code block when expression language is used to configure a service.

```
  [Symfony\Component\ExpressionLanguage\SyntaxError]
  Unexpected character "@" around position 0.
```

Commits
-------

21b00b0 Typo when expression language is used to configure a service.