[jdk17u-dev] RFR: 8331863: DUIterator_Fast used before it is constructed

[Radek Čáp]

Backport of JDK-8331863 from 21u.

Clean backport. Passed tier1 tests.

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Commit messages:
 - Backport d13f75c9ef000b05442f9f468b2f45df9a8450cf

Changes: https://git.openjdk.org/jdk17u-dev/pull/3070/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=3070&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8331863
  Stats: 2 lines in 1 file changed: 1 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/3070.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/3070/head:pull/3070

PR: https://git.openjdk.org/jdk17u-dev/pull/3070