[jdk7u] RFR: 8087283: Add support for the XML Signature here() function to the JDK XPath implementation

[Yuri Nesterenko]

I need to backport this change to 7u to facilitate other updates. Tests run fine (with testng 6)

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Commit messages:
 - Backport 22fad64529a890dd3ae8b07c7981d9a720cf8e96

Changes: https://git.openjdk.java.net/jdk7u/pull/6/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk7u&pr=6&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8087283
  Stats: 135 lines in 3 files changed: 120 ins; 1 del; 14 mod
  Patch: https://git.openjdk.java.net/jdk7u/pull/6.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk7u pull/6/head:pull/6

PR: https://git.openjdk.java.net/jdk7u/pull/6