RFR: 8340125: [lw5] null checks are not being generated for method invocations and array writes [v4]

[Vicente Romero]

> javac is not generating null checks for runtime execution for method invocations and array writes

Vicente Romero has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains six commits:

 - Merge branch 'lw5' into JDK-8340125
 - experimental code review
 - addressing review comments
 - Merge with remote branch
 - 8340125: [lw5] null checks are not being generated for method invocations and array writes
 - 8340125: [lw5] null checks are not being generated for method invocations and array writes

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Changes: https://git.openjdk.org/valhalla/pull/1251/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1251&range=03
  Stats: 348 lines in 6 files changed: 293 ins; 22 del; 33 mod
  Patch: https://git.openjdk.org/valhalla/pull/1251.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1251/head:pull/1251

PR: https://git.openjdk.org/valhalla/pull/1251