RFR: 8335967: "text-decoration: none" does not work with "A" HTML tags

[Alexey Ivanov]

After I integrated [JDK-8326734](https://bugs.openjdk.org/browse/JDK-8326734), there's no way to remove text decoration from an HTML element. The most common HTML element is `<a>` which is usually rendered _underlined_. You could add an inline style or apply a rule with `text-decoration: none` to remove underline.

This fix restores this functionality.

The test contains five cases. The first case ensures the `<a>` element is rendered with underline by default. The second and third cases verify that underline is removed if `text-decoration: none` is added to the `style` attribute or is applied by a style-sheet rule.

The fourth and fifth cases verify that underline is preserved the containing element, `<p>` in this case, has `text-decoration: underline`.

These five cases render the same way in browsers. However, the fourth and fifth cases render without underline in JDKs without JDK-8326734.

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Commit messages:
 - 8335967: "text-decoration: none" does not work with "A" HTML tags

Changes: https://git.openjdk.org/jdk/pull/20313/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20313&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8335967
  Stats: 133 lines in 2 files changed: 133 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/20313.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20313/head:pull/20313

PR: https://git.openjdk.org/jdk/pull/20313