RFR: 8284884: Replace polling with waiting in javax/swing/text/html/parser/Parser/8078268/bug8078268.java

[Alexey Ivanov]

A quick fix for the `javax/swing/text/html/parser/Parser/8078268/bug8078268.java` which replaces `Thread.sleep` in a loop with `CountDownLatch.await`.

The code is shorter and clearer.

The test fails on the builds without the fix for [JDK-8078268](https://bugs.openjdk.java.net/browse/JDK-8078268). I ran it in the CI and it passes.

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Commit messages:
 - 8284884: Drop author
 - 8284884: Replace polling with waiting in javax/swing/text/html/parser/Parser/8078268/bug8078268.java

Changes: https://git.openjdk.java.net/jdk/pull/8252/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8252&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8284884
  Stats: 21 lines in 1 file changed: 8 ins; 8 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8252.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8252/head:pull/8252

PR: https://git.openjdk.java.net/jdk/pull/8252