[jdk8u-dev] RFR: 8035467: Xerces Update: Move to Xalan based DOM L3 serializer. Deprecate Xerces' native serializer.

[Elliott Baron]

This backport is part of the effort to update Xerces in 8u to 2.12 ([JDK-8238164](https://bugs.openjdk.org/browse/JDK-8238164).

The JDK 9 commit does not apply cleanly, but only required cosmetic changes. These are due to differences in some copyright headers, and not having a `@version` Javadoc tag in the 8u version of these files.

I am concerned over deprecating the Xerces serializer. As noted in [JDK-8219692](https://bugs.openjdk.org/browse/JDK-8219692), there are behavioural changes caused by this new serializer.

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Commit messages:
 - Backport 16cbc58194d5256dcbca6fc6567f44057494b6f1

Changes: https://git.openjdk.org/jdk8u-dev/pull/89/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=89&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8035467
  Stats: 6315 lines in 50 files changed: 6205 ins; 2 del; 108 mod
  Patch: https://git.openjdk.org/jdk8u-dev/pull/89.diff
  Fetch: git fetch https://git.openjdk.org/jdk8u-dev pull/89/head:pull/89

PR: https://git.openjdk.org/jdk8u-dev/pull/89