bug #17156 [HttpFoundation] add missing symfony/polyfill-php55 dependency (xabbuh)
bug #17156 [HttpFoundation] add missing symfony/polyfill-php55 dependency (xabbuh)

This PR was merged into the 2.8 branch.

Discussion
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[HttpFoundation] add missing symfony/polyfill-php55 dependency

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #16317
| License       | MIT
| Doc PR        |

The `json_last_error_msg()` function used in the `JsonResponse` class
requires PHP 5.5.

Commits
-------

3cc4e4d add missing symfony/polyfill-php55 dependency

symfony/http-foundation,symfony/HttpFoundation