RFR: Merge lworld [v2]

[Vicente Romero]

> Merge branch 'lworld' into jep_401_javac_merge_lworld

Vicente Romero 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 eight additional commits since the last revision:

 - Merge branch 'lworld' into jep_401_javac_merge_lworld
 - 8324980: [lworld] removing dead code plus gratuitous differences with jdk/master
 - 8324864: [lworld] remove non-cyclic membership checks
 - 8194743: Compiler implementation for Statements before super()
 - 8324787: [lworld] eliminate restrictions on abstract value classes and additional refactorings
 - 8324784: [lworld] remove constant propagation code and tests
 - 8324643: [lworld] remove ACC_VALUE flag and the 'identity' modifier
 - 8324052: [lworld] remove experimental code from lworld

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Changes:
  - all: https://git.openjdk.org/valhalla/pull/985/files
  - new: https://git.openjdk.org/valhalla/pull/985/files/7a973fce..7a973fce

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=valhalla&pr=985&range=01
 - incr: https://webrevs.openjdk.org/?repo=valhalla&pr=985&range=00-01

  Stats: 0 lines in 0 files changed: 0 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/valhalla/pull/985.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/985/head:pull/985

PR: https://git.openjdk.org/valhalla/pull/985