RFR: 8284299: Handle inheritDoc misuse more gracefully [v2]

[Pavel Rappo]

> This is a straightforward change that fixes a certain type of crashes and improves diagnosability. For details, see the individual commit messages.
> 
> One non-intuitive thing is that I had to specify `-Xdoclint:none` in the test to capture the respective warnings in the output. When I omitted `-Xdoclint` option or specified it in any other way, the warnings would disappear from the console. I know the mechanics of why that happens, but am unsure if it makes sense or is a bug.

Pavel Rappo has updated the pull request incrementally with one additional commit since the last revision:

  Address feedback

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/8107/files
  - new: https://git.openjdk.java.net/jdk/pull/8107/files/429de627..191832bc

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=8107&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=8107&range=00-01

  Stats: 202 lines in 4 files changed: 100 ins; 100 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8107.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8107/head:pull/8107

PR: https://git.openjdk.java.net/jdk/pull/8107