RFR: 8249867: xml declaration is not followed by a newline

[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.

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Commit messages:
 - fix test, remove whitespace
 - 8249867: xml declaration is not followed by a newline

Changes: https://git.openjdk.java.net/jdk/pull/2041/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2041&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8249867
  Stats: 242 lines in 4 files changed: 193 ins; 1 del; 48 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