[jdk11u-dev] RFR: 8297923: java.awt.ScrollPane broken after multiple scroll up/down

[Goetz Lindenmaier]

I backport this for parity with 11.0.21-oracle.

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Commit messages:
 - Backport f18ecea50fae69e4bad8479c37701fb08c5ee460

Changes: https://git.openjdk.org/jdk11u-dev/pull/2047/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2047&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8297923
  Stats: 301 lines in 5 files changed: 291 ins; 1 del; 9 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2047.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2047/head:pull/2047

PR: https://git.openjdk.org/jdk11u-dev/pull/2047