RFR: 8264160: Regex \b is not consistent with \w without UNICODE_CHARACTER_CLASS

[Ian Graves]

Proposed change in behavior to correct inconsistencies between `\w` and `\b` metacharacters

-------------

Commit messages:
 - Fixing bad javadoc
 - Merge remote-tracking branch 'upstream/master' into bug-8264160
 - Updating spec
 - Proposed change for \b metacharacter

Changes: https://git.openjdk.java.net/jdk/pull/7539/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7539&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8264160
  Stats: 78 lines in 2 files changed: 60 ins; 6 del; 12 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7539.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7539/head:pull/7539

PR: https://git.openjdk.java.net/jdk/pull/7539