[Validator] Removed PHP <5.3.3 specific code which is not officially supported

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

There is some code in the validator component which handles a PHP bug for versions strictly inferiors to 5.3.3. Since these versions are not supported (the requirements say 5.3.3 minimum) I thought we could remove it.

Regards.