DO NOT MERGE: Disallow namespace nodes in XPointer ranges Namespace nodes must be copied to avoid use-after-free errors. But they don't necessarily have a physical representation in a document, so simply disallow them in XPointer ranges. Found with afl-fuzz. Fixes CVE-2016-4658. Bug: 36554207 Change-Id: Ie570c4a53ae8ca82ed4ca19701ab7d8ba9b0468f (cherry picked from commit cde4b40a9c17aec816c6b2577250fff9354a6f3c)