[lworld] RFR: 8287030: Remove references to Objects.newIdentity

[Roger Riggs]

`new Object()` is again a valid way to construct a simple identity object.
As per the [JEP Draft Value Objects (Preview)](https://openjdk.java.net/jeps/8277163).

The method `java.util.Objects.newIdentity()` is no longer needed

-------------

Commit messages:
 - 8287030: Remove references to Objects.newIdentity

Changes: https://git.openjdk.java.net/valhalla/pull/692/files
 Webrev: https://webrevs.openjdk.java.net/?repo=valhalla&pr=692&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8287030
  Stats: 37 lines in 6 files changed: 0 ins; 29 del; 8 mod
  Patch: https://git.openjdk.java.net/valhalla/pull/692.diff
  Fetch: git fetch https://git.openjdk.java.net/valhalla pull/692/head:pull/692

PR: https://git.openjdk.java.net/valhalla/pull/692