RFR: 6850365: closed/java/awt/Focus/ActivateFocusTest/ActivateFocusTest.html fails

[Prasanta Sadhukhan]

Test is made more robust by executing in EDT and cleanup done by frame dispose. Testing result is green.

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Commit messages:
 - 6850365: closed/java/awt/Focus/ActivateFocusTest/ActivateFocusTest.html fails
 - 6850365: closed/java/awt/Focus/ActivateFocusTest/ActivateFocusTest.html fails

Changes: https://git.openjdk.org/jdk/pull/27214/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27214&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-6850365
  Stats: 43 lines in 1 file changed: 23 ins; 14 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/27214.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27214/head:pull/27214

PR: https://git.openjdk.org/jdk/pull/27214