[lworld] RFR: 8261631: [lworld] Fatal error in C1 compiled code due to unexpected klass

[Tobias Hartmann]

An assertion in C1 compiled profiling code triggers because the actual (exact) klass of a field is not as expected. The problem should have been solved by [JDK-8260225](https://bugs.openjdk.java.net/browse/JDK-8260225) but was only partially fixed due to a typo (`!=` vs. `==`). I've also noticed that we are profiling inline types for null, which should be avoided.

Best regards,
Tobias

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Commit messages:
 - 8261631: [lworld] Fatal error in C1 compiled code due to unexpected klass

Changes: https://git.openjdk.java.net/valhalla/pull/331/files
 Webrev: https://webrevs.openjdk.java.net/?repo=valhalla&pr=331&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8261631
  Stats: 11 lines in 3 files changed: 10 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/valhalla/pull/331.diff
  Fetch: git fetch https://git.openjdk.java.net/valhalla pull/331/head:pull/331

PR: https://git.openjdk.java.net/valhalla/pull/331