[jfx17u] RFR: 8088420: JavaFX WebView memory leak via EventListener

[Ambarish Rapte]

Clean backport to `jfx17u`.

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Commit messages:
 - 8088420: JavaFX WebView memory leak via EventListener

Changes: https://git.openjdk.org/jfx17u/pull/73/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx17u&pr=73&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8088420
  Stats: 1509 lines in 11 files changed: 1503 ins; 3 del; 3 mod
  Patch: https://git.openjdk.org/jfx17u/pull/73.diff
  Fetch: git fetch https://git.openjdk.org/jfx17u pull/73/head:pull/73

PR: https://git.openjdk.org/jfx17u/pull/73