RFR: do not generate null checks for record patterns [v3]

[Vicente Romero]

> do not generate null checks for record patterns

Vicente Romero has updated the pull request incrementally with one additional commit since the last revision:

  addressing review comments

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Changes:
  - all: https://git.openjdk.org/valhalla/pull/1884/files
  - new: https://git.openjdk.org/valhalla/pull/1884/files/6cd6ebf8..b10490e3

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=valhalla&pr=1884&range=02
 - incr: https://webrevs.openjdk.org/?repo=valhalla&pr=1884&range=01-02

  Stats: 40 lines in 4 files changed: 19 ins; 20 del; 1 mod
  Patch: https://git.openjdk.org/valhalla/pull/1884.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1884/head:pull/1884

PR: https://git.openjdk.org/valhalla/pull/1884