Unit test fixes
minor #11963 Unit test fixes [HttpKernel] Fixing unit test broken since merge 4677e92ffeac80 [Validator] Fixing the way the default time zone is backed up
Merge branch '2.5'

* 2.5:
  [Debug] Restoring error handler before assertions
  Unit test fixes
  Fixed merge conflict in .travis.yml introduced in 687703a75ed741464e15b71a1e576c319865f3fd

Conflicts:
	src/Symfony/Component/Debug/Tests/ErrorHandlerTest.php