Integrated: 8310685: [lw5] adding support for null restricted types

[Vicente Romero]

initial support for null restricted types

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Commit messages:
 - removing whitespace
 - 8310685: [lw5] adding support for null restricted types

Changes: https://git.openjdk.org/valhalla/pull/872/files
 Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=872&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8310685
  Stats: 1259 lines in 21 files changed: 1206 ins; 4 del; 49 mod
  Patch: https://git.openjdk.org/valhalla/pull/872.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/872/head:pull/872

PR: https://git.openjdk.org/valhalla/pull/872