RFR: 8277240: java/awt/Graphics2D/ScaledTransform/ScaledTransform.java dialog does not get disposed [v2]

[Phil Race]

> This test has had reports of failures over the years notably on Linux.
> I think the large number of XVisuals may have something to do with it.
> I've updated it quite a bit and limited the number of dialogs it creates - we really don't need to test 300 of them
> This new version has passed hundreds of iterations.

Phil Race has updated the pull request incrementally with one additional commit since the last revision:

  8277240

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Changes:
  - all: https://git.openjdk.org/jdk/pull/21942/files
  - new: https://git.openjdk.org/jdk/pull/21942/files/4118acc9..8583bd1c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21942&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21942&range=00-01

  Stats: 22 lines in 1 file changed: 4 ins; 10 del; 8 mod
  Patch: https://git.openjdk.org/jdk/pull/21942.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21942/head:pull/21942

PR: https://git.openjdk.org/jdk/pull/21942