[jfx11u] RFR: 8242544: CMD+ENTER key event crashes the application when invoked on dialog

[Kevin Rushforth]

Clean backport to `jfx11u`.

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Commit messages:
 - 8242544: CMD+ENTER key event crashes the application when invoked on dialog

Changes: https://git.openjdk.java.net/jfx11u/pull/72/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx11u&pr=72&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8242544
  Stats: 4 lines in 1 file changed: 3 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jfx11u/pull/72.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx11u pull/72/head:pull/72

PR: https://git.openjdk.java.net/jfx11u/pull/72