RFR: 8277560: Remove WorkerDataArray::_is_serial

Mon Nov 22 14:03:37 UTC 2021

Simple change of removing effectively dead code.

Test: build

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Commit messages:
 - WorkerDataArray._is_serial

Changes: https://git.openjdk.java.net/jdk/pull/6502/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6502&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8277560
  Stats: 35 lines in 2 files changed: 5 ins; 15 del; 15 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6502.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6502/head:pull/6502

PR: https://git.openjdk.java.net/jdk/pull/6502