RFR: 8169475 : WheelModifier.java fails by timeout [v2]

[Renjith Kannath Pariyangad]

> Hi Reviewers,
> 
> I have added additional CountDownLatch for making sure button is visible before proceeding,(observe this was one of the key reason for failure) so this helps to improve test case stability. Modified _await()_ function by adding 1sec timeout with exception, this will help to reduce total execution time in case of failure. 
> Please review and let me know your suggestions, if any.

Renjith Kannath Pariyangad has updated the pull request incrementally with one additional commit since the last revision:

  Added null check before frame dispose

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Changes:
  - all: https://git.openjdk.org/jdk/pull/16281/files
  - new: https://git.openjdk.org/jdk/pull/16281/files/c1d7cfd1..2ef843df

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16281&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16281&range=00-01

  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/16281.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16281/head:pull/16281

PR: https://git.openjdk.org/jdk/pull/16281