Revert "Fix handlesOwnChildren check in getRelativeOffset"

Breaks ve.ce.Document.getRelativeRange tests in VE-MW

This reverts commit d6316f560ea65cd9451406b8d5b5124fe97c5d42.

Change-Id: Ibb06be60d330654669e69852814477fc91cedee7
Merge "Revert "Fix handlesOwnChildren check in getRelativeOffset""