[jdk21u-dev] RFR: 8323801: <s> tag doesn't strikethrough the text

[Martin Doerr]

Backport of [JDK-8323801](https://bugs.openjdk.org/browse/JDK-8323801). Clean except Copyright year change.

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Commit messages:
 - Backport 80b63b67293970936d57ae4375ad76cd2b11a333

Changes: https://git.openjdk.org/jdk21u-dev/pull/660/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=660&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8323801
  Stats: 127 lines in 2 files changed: 117 ins; 0 del; 10 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/660.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/660/head:pull/660

PR: https://git.openjdk.org/jdk21u-dev/pull/660