[jdk11u-dev] RFR: 8213926: WB_EnqueueInitializerForCompilation requests compilation for NULL

[Amos Shi]

Backport of [JDK-8213926](https://bugs.openjdk.org/browse/JDK-8213926)

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Commit messages:
 - Backport 6b0d1af7fa2ab044621bcc939d63c906f3c60c28

Changes: https://git.openjdk.org/jdk11u-dev/pull/2320/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2320&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8213926
  Stats: 5 lines in 1 file changed: 4 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2320.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2320/head:pull/2320

PR: https://git.openjdk.org/jdk11u-dev/pull/2320