[jfx17u] RFR: 8322703: Intermittent crash in WebView in a JFXPanel from IME calls on macOS

[Jose Pereda]

Almost clean backport of 8322703: Intermittent crash in WebView in a JFXPanel from IME calls on macOS

Reviewed-by: jbhaskar, arapte

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Commit messages:
 - 8322703: Intermittent crash in WebView in a JFXPanel from IME calls on macOS

Changes: https://git.openjdk.org/jfx17u/pull/179/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx17u&pr=179&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8322703
  Stats: 63 lines in 1 file changed: 34 ins; 18 del; 11 mod
  Patch: https://git.openjdk.org/jfx17u/pull/179.diff
  Fetch: git fetch https://git.openjdk.org/jfx17u.git pull/179/head:pull/179

PR: https://git.openjdk.org/jfx17u/pull/179