RFR: 8249867: xml declaration is not followed by a newline [v2]

[Joe Wang]

> Please review a patch to add an explicit control over whether a newline should be added after the XML header. This is done by adding a DOM LSSerializer property "jdk-is-standalone" and System property "jdk.xml.isStandalone". 
> 
> This change addresses an incompatibility introduced during 7u4 as an update to Xalan 2.7.1.

Joe Wang has updated the pull request incrementally with one additional commit since the last revision:

  Update: add javadoc for impl specific features and properties in module-info; update the patch accordingly.

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/2041/files
  - new: https://git.openjdk.java.net/jdk/pull/2041/files/3ab9fed9..a3591aa7

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=2041&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=2041&range=00-01

  Stats: 249 lines in 5 files changed: 233 ins; 5 del; 11 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2041.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2041/head:pull/2041

PR: https://git.openjdk.java.net/jdk/pull/2041