fix session restart on PHP 5.3

this also removes some useless code
bug #12961 fix session restart on PHP 5.3 (Tobion)

This PR was merged into the 2.3 branch.

Discussion
----------

fix session restart on PHP 5.3

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | no
| Fixed tickets | #12562
| License       | MIT
| Doc PR        | -

this also removes some useless code

Commits
-------

b9d3c92 fix session restart on PHP 5.3
remove short array syntax

The short array syntax was introduced in PHP 5.4 and therefore leads
to failing tests when executed in PHP 5.3 environments.
minor #12962 [SecurityBundle] remove short array syntax (xabbuh)

This PR was merged into the 2.3 branch.

Discussion
----------

[SecurityBundle] remove short array syntax

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

The short array syntax was introduced in PHP 5.4 and therefore leads
to failing tests when executed in PHP 5.3 environments.

Commits
-------

697ce4d remove short array syntax
Merge branch '2.3' into 2.5

* 2.3:
  remove short array syntax
  fix session restart on PHP 5.3