Fix "Array was modified outside object" in ResizeFormListener.

The onSubmit() method of the ResizeFormListener class is assuming the data is an array, and calling unset directly inside a foreach. This works fine in most scenarios, but if data is an instance of IteratorAggregate, it breaks with the following error:

Symfony\Component\Form\Extension\Core\EventListener\ResizeFormListener::onSubmit(): ArrayIterator::next(): Array was modified outside object and internal position is no longer valid in ./vendor/symfony/symfony/src/Symfony/Component/Form/Extension/Core/EventListener/ResizeFormListener.php line 142

This is because the foreach loop is using an Iterator in the background, but the ResizeFormListener has unset the underlying data directly, causing the Iterator and data to be out of sync. When the data is an instance of IteratorAggregate, the loop should use the iterator directly and not rely on foreach.

The onSubmit method has been updated accordingly.
Added failing test
Revert "Fix "Array was modified outside object" in ResizeFormListener."
Merge branch '2.3' into 2.4

* 2.3:
  Revert "Fix "Array was modified outside object" in ResizeFormListener."
  Added failing test
  bumped Symfony version to 2.3.11
  updated VERSION for 2.3.10
  update CONTRIBUTORS for 2.3.10
  updated CHANGELOG for 2.3.10
  [Console] removed problematic regex
  [DomCrawler] Added support for <area> tags to be treated as links
  Fix "Array was modified outside object" in ResizeFormListener.

Conflicts:
	src/Symfony/Component/HttpKernel/Kernel.php