[jfx21u] RFR: 8330462: StringIndexOutOfBoundException when typing anything into TextField

[Jose Pereda]

Hi all,

This pull request contains a backport of commit [d3da033a](https://github.com/openjdk/jfx/commit/d3da033a2dd5c287733545935242a8d1f71c0554) from the [openjdk/jfx](https://git.openjdk.org/jfx) repository.

The commit being backported was authored by Oliver Kopp on 8 May 2024 and was reviewed by Andy Goryachev, Kevin Rushforth and Ambarish Rapte.

The backport is almost clean: While cherry picking the mainline commit, a minor merge conflict was shown at the file `tests/system/src/test/.classpath`: The mainline file has a few additional exports compared to 21u, which are not needed here.

Thanks!

-------------

Commit messages:
 - Backport d3da033a2dd5c287733545935242a8d1f71c0554

Changes: https://git.openjdk.org/jfx21u/pull/57/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx21u&pr=57&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8330462
  Stats: 147 lines in 5 files changed: 142 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/jfx21u/pull/57.diff
  Fetch: git fetch https://git.openjdk.org/jfx21u.git pull/57/head:pull/57

PR: https://git.openjdk.org/jfx21u/pull/57