[lilliput-jdk17u:lilliput] RFR: 8304410: [Lilliput/JDK17] Remove unneeded code in ContiguousSpace::object_iterate_from()

[Roman Kennke]

There is some code in space.cpp that resolves a forwarding pointer to get to the Klass* of an object under Lilliput, but it is not necessary and actually causes harm (the null-check doesn't really make sense when the object is indeed forwarded, but we should not observe a forwarded object to begin with). It is not in upstream JDK(21) version of Lilliput and removing it causes no harm.

Testing:
 - [x] tier1 -XX:+UseCompactHeaders
 - [x] tier1 -XX:-UseCompactHeaders
 - [x] tier2 -XX:+UseCompactHeaders
 - [x] tier2 -XX:-UseCompactHeaders

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Commit messages:
 - 8304410: [Lilliput/JDK17] Remove unneeded code in ContiguousSpace::object_iterate_from()

Changes: https://git.openjdk.org/lilliput-jdk17u/pull/13/files
 Webrev: https://webrevs.openjdk.org/?repo=lilliput-jdk17u&pr=13&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8304410
  Stats: 5 lines in 1 file changed: 0 ins; 5 del; 0 mod
  Patch: https://git.openjdk.org/lilliput-jdk17u/pull/13.diff
  Fetch: git fetch https://git.openjdk.org/lilliput-jdk17u pull/13/head:pull/13

PR: https://git.openjdk.org/lilliput-jdk17u/pull/13