[BZ 1150624] Avoid DTD retrieval even if the DOM has it. Also avoid parsing logic to determine if the dtd is on the document; let the transformer handle that at output time.
(cherry picked from commit e73af2af73f53511bef5752034c383112a553d98)

Signed-off-by: John Mazzitelli <mazz@redhat.com>
[BZ 1150624] Add additional code to prevent attempts to load DTD.
(cherry picked from commit 3064b71e8a10c2987c9c45188975a07e2462caa7)

Signed-off-by: John Mazzitelli <mazz@redhat.com>