RFR: 8065097: [macosx] javax/swing/Popup/TaskbarPositionTest.java fails because Popup is one pixel off [v3]

[Prasanta Sadhukhan]

> Test seems to fail in macOS citing popup location is 1 pixel off compared to combobox position ie
> `p.y 154 cpos.y 155`
> 
> But in macOS, popup location, if 1st entry is selected, is 1 pixel higher than combobox so it's expected as can be seen below
> <img width="661" alt="Screenshot 2022-06-29 at 1 53 42 PM" src="https://user-images.githubusercontent.com/43534309/176389227-4e568117-ffce-4b4a-92d7-ab5c78c4ce08.png">
> 
> so test is updated to add 1 pixel to popup location. 
> It will not affect windows and linux as popup is placed below the combobox in those platforms so 1 pixel higher will not make any difference.
> Also, added some stability fixes..Test passed for several iterations in all platforms in CI..

Prasanta Sadhukhan has updated the pull request incrementally with one additional commit since the last revision:

  Review comments addressed

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/9321/files
  - new: https://git.openjdk.org/jdk/pull/9321/files/c159f874..2ad78ef0

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9321&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9321&range=01-02

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/9321.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9321/head:pull/9321

PR: https://git.openjdk.org/jdk/pull/9321