RFR: 8191460: crash in Annotate with duplicate declaration and annotation processing enabled

[Vicente Romero]

This PR is removing an assertion in `com.sun.tools.javac.comp.Annotate`. The assertion was being thrown for code that was erroneous in the first place. Basically having:

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Commit messages:
 - 8191460: crash in Annotate with duplicate declaration and annotation processing enabled

Changes: https://git.openjdk.org/jdk/pull/16443/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16443&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8191460
  Stats: 170 lines in 2 files changed: 162 ins; 8 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/16443.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16443/head:pull/16443

PR: https://git.openjdk.org/jdk/pull/16443