RFR: 8335623: Cleanup HtmlTag.HtmlTag and make the Aria role attribute global

[Nizar Benalla]

Can I please get a review for this small change? It removes some lines that are no longer necessary and sets the Aria role as global.
Thanks in advance.

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Commit messages:
 - Remove redundant lines in `HtmlTag` and make Role attribute global

Changes: https://git.openjdk.org/jdk/pull/20007/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20007&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8335623
  Stats: 21 lines in 1 file changed: 0 ins; 20 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/20007.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20007/head:pull/20007

PR: https://git.openjdk.org/jdk/pull/20007