RFR: JDK-8222323: ChildAlwaysOnTopTest.java fails with "RuntimeException: Failed to unset alwaysOnTop" [v3]

[Harshitha Onkar]

> This test case tests the functionality of `setAlwaysOnTop`. 
> Documentation on `setAlwaysOnTop`: [Link](https://docs.oracle.com/en/java/javase/17/docs/api/java.desktop/java/awt/Window.html#setAlwaysOnTop(boolean))
> 
> The following test case was seen to fail on windows and linux platforms. With the proposed fix, the test case works on all platforms.
> 
> The test case tests `alwaysOnTop` for the following three cases:
> 
> 1.	JDialog with no parent/owner
> 2.	JDialog with JFrame as owner
> 3.	JDialog with another JDialog as owner
> 
> Each of the three cases mentioned above is tested under 3 scenarios:
> ![Screen Shot 2022-05-02 at 2 02 30 PM](https://user-images.githubusercontent.com/95945681/166327299-0fb5ce14-478d-4dee-a03a-1009a8e17047.png)

Harshitha Onkar has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:

 - Merge branch 'master' into AlwaysOnTop_8222323
 - added changes to continue testing and exception thrown at end in case of failure
 - test case changes for alwaysOnTop

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/8509/files
  - new: https://git.openjdk.java.net/jdk/pull/8509/files/396d5659..e4b7740d

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=8509&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=8509&range=01-02

  Stats: 21206 lines in 574 files changed: 13670 ins; 3601 del; 3935 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8509.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8509/head:pull/8509

PR: https://git.openjdk.java.net/jdk/pull/8509