RFR: 8297556: Parse::check_interpreter_type fails with assert "must constrain OSR typestate"

[Roland Westrelin]

With 6312651 (Compiler should only use verified interface types for
optimization), I changed when the _klass field for an array in the
type system would be null. Before, there was an assumption that any
type (other than top, bottom) could be represented with a non null
_klass field. With 6312651, there are types that are impossible to
represent with a single klass pointer so now, the _klass field is only
guaranteed non null for an array of basic type. When I made that
change, I went over uses of the _klass field for anything other than
an array of basic type and fixed the code so it uses something other
than the _klass field. This is a place I missed.

(I made some of the changes for the _klass field after Vladimir I ran
extensive testing for the patch so that could explain why this issue
was missed)

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Commit messages:
 - test
 - fix

Changes: https://git.openjdk.org/jdk/pull/11356/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11356&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8297556
  Stats: 50 lines in 2 files changed: 46 ins; 2 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/11356.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11356/head:pull/11356

PR: https://git.openjdk.org/jdk/pull/11356