Fix `extract` method to avoid recalculating count() for each iteration.

Cache the value of `count($attributes)` to avoid recalculating it for each iteration of the loop.

Since this count will never change during the method execution, this change make the code a bit more efficient.
Merge branch '2.2' into 2.3

* 2.2:
  updated VERSION for 2.2.11
  update CONTRIBUTORS for 2.2.11
  updated CHANGELOG for 2.2.11
  [HttpKernel] made a small optimization to Bundle initialization
  minor optimalization at bundle initialization
  [EventDispatcher] tweaked README
  removed observer pattern, in favour of mediator
  [DoctrineBridge] normalized class names in the ORM type guesser
  Fix `extract` method to avoid recalculating count() for each iteration.
  use the correct class name to retrieve mapped class' metadata and repository
  [WebProfilerBundle] Fixed js escaping in time.html.twig

Conflicts:
	src/Symfony/Bundle/WebProfilerBundle/Resources/views/Collector/time.html.twig
	src/Symfony/Component/HttpKernel/Kernel.php