RFR: 8266571: Sequenced Collections

[Stuart Marks]

PR for Sequenced Collections implementation.

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

Commit messages:
 - Specification cleanups.
 - Update spec of CopyOnWriteArrayList::reversed.
 - Move AbstractViewCollection to AbstractMap.ViewCollection to avoid exposing it publicly.
 - Merge branch 'master' into JDK-8266571-SequencedCollections
 - Merge branch 'master' into JDK-8266571-SequencedCollections
 - Fix indentation.
 - Merge branch 'master' into JDK-8266571-SequencedCollections
 - Add thread-safe reversed view of CopyOnWriteArrayList
 - Add CopyOnWriteArrayList to the tests.
 - Add ListIterator and subList ListIterator modification tests.
 - ... and 64 more: https://git.openjdk.org/jdk/compare/21169285...31f7d102

Changes: https://git.openjdk.org/jdk/pull/7387/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=7387&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8266571
  Stats: 6524 lines in 34 files changed: 6410 ins; 9 del; 105 mod
  Patch: https://git.openjdk.org/jdk/pull/7387.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/7387/head:pull/7387

PR: https://git.openjdk.org/jdk/pull/7387