RFR: 8350178: Incorrect comment after JDK-8345580 [v2]

[SendaoYan]

> Hi all,
> In [JDK-8345580](https://bugs.openjdk.org/browse/JDK-8345580), the const modifier for variable Node::_idx has been removed, but the constant description for variable Node::_idx leave unchange. The related description should be updated.
> 
> Only touch the comments, no risk.

SendaoYan has updated the pull request incrementally with one additional commit since the last revision:

  Remove extra a whitespace

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/23659/files
  - new: https://git.openjdk.org/jdk/pull/23659/files/0f65a393..78fd3da5

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=23659&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=23659&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/23659.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23659/head:pull/23659

PR: https://git.openjdk.org/jdk/pull/23659