make Node.type_id field private
Disable intermittently failing Document-characterSet-normalization.html (fixes #3209).

As we currently don't support anything but utf-8, this is not a particularly
useful test to run.
Merge pull request #3210 from seanmonstar/private-node-type-id

make Node.type_id field private, access through type_id()
Merge pull request #3226 from Ms2ger/3209-disable

Disable intermittently failing Document-characterSet-normalization.html (fixes #3209); r=jdm