Fix bug #65196

Passing DOMDocumentFragment to DOMDocument::saveHTML()
produces invalid markup, because a DocumentFragment is just a container
for child nodes and not a real node itself.
Merge branch 'PHP-5.4' into PHP-5.5

* PHP-5.4:
  Fix bug #65196
BFN
Merge branch 'PHP-5.5' into PHP-5.6

* PHP-5.5:
  BFN
  Fix bug #65196
Merge branch 'PHP-5.6'

* PHP-5.6:
  BFN
  Fix bug #65196