RFR: 8331168: Introduce PredicateEntryIterator to iterate through predicate entries [v2]

[Christian Hagedorn]

> This is another small PR split off from the complete fix for Assertion Predicates.
> 
> Changes include:
> - Replace predicate matching/skipping code in `build_loop_late_post_work()` to use dedicated walker (i.e. new `PredicateEntryIterator` class) which uses predicate classes.
> - New predicate helper classes to improve readability.
> - Simple typos and code style updates.
> 
> Thanks,
> Christian

Christian Hagedorn has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:

 - Introduce is_strict_dominator()
 - Merge branch 'master' into JDK-8331168
 - 8331168: Introduce PredicateEntryIterator to iterate through predicate entries

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/19716/files
  - new: https://git.openjdk.org/jdk/pull/19716/files/788f6bf2..78b9da90

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=19716&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=19716&range=00-01

  Stats: 15039 lines in 600 files changed: 6234 ins; 7264 del; 1541 mod
  Patch: https://git.openjdk.org/jdk/pull/19716.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19716/head:pull/19716

PR: https://git.openjdk.org/jdk/pull/19716