[lworld] Integrated: 8267910: [lworld] Javac fails to implicitly type abstract classes as implementing IdentityObject

[Srikanth Adayapalam]

Align with deraft spec on implicit typing of abstract classes

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Commit messages:
 - 8267910: Javac fails to implicitly type abstract classes as implementing IdentityObject

Changes: https://git.openjdk.java.net/valhalla/pull/434/files
 Webrev: https://webrevs.openjdk.java.net/?repo=valhalla&pr=434&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8267910
  Stats: 141 lines in 11 files changed: 119 ins; 7 del; 15 mod
  Patch: https://git.openjdk.java.net/valhalla/pull/434.diff
  Fetch: git fetch https://git.openjdk.java.net/valhalla pull/434/head:pull/434

PR: https://git.openjdk.java.net/valhalla/pull/434