Unify null comparisons
remove unused imports
minor #11484 remove unused imports (xabbuh)

This PR was merged into the 2.3 branch.

Discussion
----------

remove unused imports

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

Commits
-------

9cd059e remove unused imports
Merge branch '2.3' into 2.4

* 2.3:
  Update validators.eu.xlf
  fixed CS
  remove unused imports
  Unify null comparisons
  [EventDispatcher] don't count empty listeners
  [Process] Fix unit tests in sigchild environment
  [Process] fix signal handling in wait()
  [BrowserKit] refactor code and fix unquoted regex
  Fixed server HTTP_HOST port uri conversion
  Bring code into standard
  [Process] Add test to verify fix for issue #11421
  [Process] Fixes issue #11421
  [DependencyInjection] Pass a Scope instance instead of a scope name.

Conflicts:
	src/Symfony/Component/EventDispatcher/Tests/EventDispatcherTest.php
Merge branch '2.4' into 2.5

* 2.4:
  Update validators.eu.xlf
  fixed CS
  remove unused imports
  [Routing] simplify the XML schema file
  Unify null comparisons
  [EventDispatcher] don't count empty listeners
  [Process] Fix unit tests in sigchild environment
  [Process] fix signal handling in wait()
  [BrowserKit] refactor code and fix unquoted regex
  Fixed server HTTP_HOST port uri conversion
  [MonologBridge] fixed Console handler priorities
  Bring code into standard
  [Process] Add test to verify fix for issue #11421
  [Process] Fixes issue #11421
  [DependencyInjection] Pass a Scope instance instead of a scope name.

Conflicts:
	src/Symfony/Bundle/FrameworkBundle/Test/WebTestCase.php
	src/Symfony/Component/DependencyInjection/Tests/Dumper/GraphvizDumperTest.php
	src/Symfony/Component/PropertyAccess/Tests/PropertyAccessorCollectionTest.php
Merge branch '2.5'

* 2.5:
  Update validators.eu.xlf
  fixed CS
  remove unused imports
  [Validator] Added markObjectAsInitialized() and isObjectInitialized() to ExecutionContextInterface
  [Validator] Fixed doc block
  [Routing] simplify the XML schema file
  Unify null comparisons
  [EventDispatcher] don't count empty listeners
  [Process] Fix unit tests in sigchild environment
  [Process] fix signal handling in wait()
  [BrowserKit] refactor code and fix unquoted regex
  Fixed server HTTP_HOST port uri conversion
  [HttpFoundation] moved test file to the right directory
  [Validator] Made sure that context changes don't leak out of (Contextual)ValidatorInterface
  [MonologBridge] fixed Console handler priorities
  Bring code into standard
  [Process] Add test to verify fix for issue #11421
  [Process] Fixes issue #11421
  [DependencyInjection] Pass a Scope instance instead of a scope name.