RFR: Merge lworld

[Vicente Romero]

# Conflicts:
#	src/jdk.compiler/share/classes/com/sun/tools/javac/code/Flags.java
#	src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Attr.java
#	src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Check.java

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Commit messages:
 - Merge branch 'lworld' into universal-tvars_merge_lworld
 - 8279431: [lworld] Withdraw all support for ref-default classes
 - 8279377: [lworld] Javac Parser still has stale code supporting nullable projection types from a previous era
 - 8274800: [lworld] Primitive classes can't be retransformed
 - 8278352: [lworld] nmethod assembly snippet in hs_err file misses method name and parameters
 - 8278350: [lworld] Compiler test failures after merge with mainline
 - Merge jdk
 - 8274685: Documentation suggests there are ArbitrarilyJumpableGenerator when none
 - 8273792: JumpableGenerator.rngs() documentation refers to wrong method
 - 8277428: G1: Move and inline G1STWIsAliveClosure::do_object_b
 - ... and 1123 more: https://git.openjdk.java.net/valhalla/compare/bc2580e1...443c8df8

The webrevs contain the adjustments done while merging with regards to each parent branch:
 - universal-tvars: https://webrevs.openjdk.java.net/?repo=valhalla&pr=594&range=00.0
 - lworld: https://webrevs.openjdk.java.net/?repo=valhalla&pr=594&range=00.1

Changes: https://git.openjdk.java.net/valhalla/pull/594/files
  Stats: 994625 lines in 4029 files changed: 527788 ins; 446352 del; 20485 mod
  Patch: https://git.openjdk.java.net/valhalla/pull/594.diff
  Fetch: git fetch https://git.openjdk.java.net/valhalla pull/594/head:pull/594

PR: https://git.openjdk.java.net/valhalla/pull/594