RFR: JDK-8307184: Incorrect/inconsistent specification and implementation for Elements.getDocComment [v6]

[Joe Darcy]

> Start by just reformatting the existing specs to highlight subsequent spec changes.

Joe Darcy has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains seven additional commits since the last revision:

 - Respond to review comments.
 - Merge branch 'master' into JDK-8307184
 - Appease jcheck.
 - Updates.
 - Add tests; adjust spec.
 - Update non-beginning, non-eneding lines of the spec.
 - JDK-8307184: Incorrect/inconsistent specification and implementation for Elements.getDocComment

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/15062/files
  - new: https://git.openjdk.org/jdk/pull/15062/files/9b436d26..79b11319

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15062&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15062&range=04-05

  Stats: 2840 lines in 123 files changed: 1130 ins; 859 del; 851 mod
  Patch: https://git.openjdk.org/jdk/pull/15062.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15062/head:pull/15062

PR: https://git.openjdk.org/jdk/pull/15062