[jdk11u-dev] RFR: 8305505: NPE in javazic compiler

[Amos Shi]

Backport of [JDK-8305505](https://bugs.openjdk.org/browse/JDK-8305505)
- Clean Backport

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Commit messages:
 - Backport 544bd260b6eb7bc7cf79a3739cc94bad658d7d15

Changes: https://git.openjdk.org/jdk11u-dev/pull/2367/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2367&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8305505
  Stats: 5 lines in 1 file changed: 1 ins; 1 del; 3 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2367.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2367/head:pull/2367

PR: https://git.openjdk.org/jdk11u-dev/pull/2367