[11u] RFR: 8261209: isStandalone property: remove dependency on pretty-print

[Doerr, Martin]

Hi,

JDK-8261209 is backported to 11.0.11-oracle. I'd like to backport it for parity.
The actual fix is trivial, but the remainder of the original patch doesn't apply to 11u.

So I suggest the following:
- Only take the real fix which is in ToXMLStream.java (LastModified timestamp doesn't exist in 11u).
- Skip module-info.java: The modified comments don't exist in 11u.
- Skip PrettyPrintTest.java: The modified parts of the test don't exist in 11u.

The existing tests are still passing with the fix.

Original bug:
https://bugs.openjdk.java.net/browse/JDK-8261209

Original change:
https://github.com/openjdk/jdk/commit/7c565f8b

11u backport:
http://cr.openjdk.java.net/~mdoerr/8261209_xml_11u/webrev.00/

Please review.

Best regards,
Martin