Returns the parent of this GPathResult. If this GPathResult has no parent the GPathResult itself is returned.
This is no navigation in the XML tree. It is backtracking on the GPath expression chain.
It is the bevavior of parent() prior to 2.2.0.
Backtracking on '..' actually goes down one level in the tree again.
find() and findAll() are popped along with the level they have been applied to.