[Twig] fixed TwigEngine::exists() method when a template contains a syntax error (closes #88546)
Merge branch '2.2' into 2.3

* 2.2:
  return 0 if there is no valid data
  [Tests] Tests on php 5.5 should pass
  [Twig] fixed TwigEngine::exists() method when a template contains a syntax error (closes #88546)