[jdk11u-dev] RFR: 8272966: test/jdk/java/awt/Robot/FlushCurrentEvent.java fails by timeout

[Sergey Bylokhov]

The test case backported by the [JDK-8267722](https://bugs.openjdk.java.net/browse/JDK-8267722) is too strict for jdk11. It uses the `Robot.delay()` method which is `synchronised` in jdk11 and this caused a deadlock.

Main thread: `synchronized robot.waitForIdle()` - > trying to synchronously execute the code on EDT
EDT: trying to call `synchronized Robot.delay()`

The synchronized keyword was removed by the [JDK-8210231](https://bugs.openjdk.java.net/browse/JDK-8210231) in JDK15 and it cannot be backported due to compatibility reasons.

The solution is to relax this part of the test which does not affect its ability to verify the fix for JDK-8196100

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Commit messages:
 - Update FlushCurrentEvent.java

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/309/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=309&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8272966
  Stats: 9 lines in 1 file changed: 7 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/309.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/309/head:pull/309

PR: https://git.openjdk.java.net/jdk11u-dev/pull/309