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
1 file changed