[jdk11u-dev] RFR: 8271519: java/awt/event/SequencedEvent/MultipleContextsFunctionalTest.java failed with "Total [200] - Expected [400]"

[Amos]

- This is the back port of [JDK-8271519](https://bugs.openjdk.org/browse/JDK-8271519)
- The original commit is https://github.com/openjdk/jdk/commit/9f94cbec51df7556d34fffa810e59dd9eb8521df
- The test case has been verified working in local

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Commit messages:
 - Backport 9f94cbec51df7556d34fffa810e59dd9eb8521df

Changes: https://git.openjdk.org/jdk11u-dev/pull/2145/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2145&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8271519
  Stats: 5 lines in 1 file changed: 1 ins; 1 del; 3 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2145.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2145/head:pull/2145

PR: https://git.openjdk.org/jdk11u-dev/pull/2145