RFR: JDK-8283661: Unexpected TypeElement in ANALYZE TaskEvent

[Jonathan Gibbons]

Please review a moderately simple set of changes to address issues found when using TaskListener to monitor the compilation of module-info and package-info files.

A new test is provided.

Full details and explanation in the JBS issue.

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Commit messages:
 - JDK-8283661: Unexpected TypeElement in ANALYZE TaskEvent

Changes: https://git.openjdk.java.net/jdk/pull/7949/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7949&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8283661
  Stats: 197 lines in 3 files changed: 188 ins; 2 del; 7 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7949.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7949/head:pull/7949

PR: https://git.openjdk.java.net/jdk/pull/7949