RFR: JDK-8305673: Convert DocCommentParser to use enhanced switch [v2]

[Jonathan Gibbons]

> Please review more cleanup for DocCommentParser, primarily focused on using enhanced switch statements and expressions.
> 
> The first commit is mostly IDE-automated.
> The second commit is manual.
> 
> All change are "local".  There are two remaining switch statements using the old form that have non-trivial fall-through code, which could/should be moved out into separate methods.

Jonathan Gibbons 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 three additional commits since the last revision:

 - Merge remote-tracking branch 'upstream/master' into 8305673.dcp-enhanced-switch
 - convert additional switch statements
 - JDK-8305673: Convert DocCommentParser to use enhanced switch

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/13362/files
  - new: https://git.openjdk.org/jdk/pull/13362/files/5501bf21..3f2c558a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13362&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13362&range=00-01

  Stats: 15129 lines in 504 files changed: 7636 ins; 6268 del; 1225 mod
  Patch: https://git.openjdk.org/jdk/pull/13362.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13362/head:pull/13362

PR: https://git.openjdk.org/jdk/pull/13362