[lworld] RFR: 8320080: [lworld] SubTypeCheckNode::sub asserts with "should be not null"

[Tobias Hartmann]

Similar to [JDK-8315744](https://bugs.openjdk.org/browse/JDK-8315744), we hit an assert because the subtype of a SubTypeCheckNode is not known to be non-null. The problem is that when pushing casts up through InlineTypeNodes in `ConstraintCastNode::Ideal`, we lose track of the null-free information.

I also re-added still required `T_PRIMITIVE_OBJECT` in the compiler replay implementation that I accidentally removed with https://git.openjdk.org/valhalla/pull/946.

Thanks,
Tobias

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Commit messages:
 - 8320080: [lworld] SubTypeCheckNode::sub asserts with "should be not null"

Changes: https://git.openjdk.org/valhalla/pull/956/files
 Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=956&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8320080
  Stats: 22 lines in 4 files changed: 22 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/valhalla/pull/956.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/956/head:pull/956

PR: https://git.openjdk.org/valhalla/pull/956