[lworld] Integrated: 8286807: Revert experimental special treatment given to new Object() instantiation.

[Srikanth Adayapalam]

Revert the changes made for:
    JDK-8237073 - Need special handling of jlO constructor invocation
    JDK-8281026 - Allow for compiler.note.cant.instantiate.object.directly to be suppressed via an option
    JDK-8280456 - javac should allow compilation with abstract java.lang.Object class

    The revert of JDK-8283573 - a hotspot fix for "Make Object an abstract class" will need to happen on its own.

    The current commit makes j.l.O concrete again, but leaves in the method java.util.Objects.newIdentity() and the class java.lang.Identity intact and these will have to be removed by a separate follow up patch from the core libraries component.

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Commit messages:
 - 8286807: Revert experimental special treatment given to new Object() instantiation.

Changes: https://git.openjdk.java.net/valhalla/pull/691/files
 Webrev: https://webrevs.openjdk.java.net/?repo=valhalla&pr=691&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8286807
  Stats: 188 lines in 45 files changed: 0 ins; 129 del; 59 mod
  Patch: https://git.openjdk.java.net/valhalla/pull/691.diff
  Fetch: git fetch https://git.openjdk.java.net/valhalla pull/691/head:pull/691

PR: https://git.openjdk.java.net/valhalla/pull/691