RFR: 8301630: C2: 8297933 broke type speculation in some cases

[Roland Westrelin]

With 8297933, a TypeAryPtr is a lot more likely to have a null _klass
and that breaks TypePtr::speculative_type().

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Commit messages:
 - whitespaces
 - test & fix

Changes: https://git.openjdk.org/jdk/pull/12368/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12368&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8301630
  Stats: 104 lines in 2 files changed: 103 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/12368.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12368/head:pull/12368

PR: https://git.openjdk.org/jdk/pull/12368