[jdk11u-dev] RFR: 8239502: [TEST_BUG] Test javax/swing/text/FlowView/6318524/bug6318524.java never fails

[Goetz Lindenmaier]

I backport this for parity with 11.0.15-oracle.

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Commit messages:
 - Backport b7425b63f6b69ba8709664377b4e037176ab6139

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/735/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=735&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8239502
  Stats: 194 lines in 1 file changed: 194 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/735.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/735/head:pull/735

PR: https://git.openjdk.java.net/jdk11u-dev/pull/735