Fix Crawler::children() to not trigger a notice for childless node
Merge branch '2.1' into 2.2

* 2.1:
  [CssSelector] Fix :nth-last-child() translation
  Fix Crawler::children() to not trigger a notice for childless node
Merge branch '2.2' into 2.3

* 2.2:
  [CssSelector] Fix :nth-last-child() translation
  Fix Crawler::children() to not trigger a notice for childless node

Conflicts:
	src/Symfony/Component/CssSelector/Node/FunctionNode.php
	src/Symfony/Component/CssSelector/Tests/Node/FunctionNodeTest.php