[jdk11u-dev] Integrated: 8266615: C2 incorrectly folds subtype checks involving an interface array

[Roland Westrelin]

Backport of 8266615

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Commit messages:
 - Backport ce88b334884b6cc76bd938a8a8e6a9b28a777cb8

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/15/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=15&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8266615
  Stats: 87 lines in 2 files changed: 85 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/15.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/15/head:pull/15

PR: https://git.openjdk.java.net/jdk11u-dev/pull/15