[lworld] RFR: 8374786: [lworld] C2: Missing asserts in parse3.cpp after merging JDK-8341411

[Christian Hagedorn]

When merging in [JDK-8341411](https://bugs.openjdk.org/browse/JDK-8341411), we wrongly dropped the following two similar asserts:

assert(C->get_alias_index(adr_type) == C->get_alias_index(_gvn.type(adr)->isa_ptr()),
    "slice of address and input slice don't match");

This was difficult to spot because `adr` was only defined further down in the code at the time of the merge. [JDK-8357474](https://bugs.openjdk.org/browse/JDK-8357474) moved `adr` up to the place where we also define it in mainline which is how it was noticed that they are missing. This patch simply adds the asserts again

Thanks,
Christian

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Commit messages:
 - 8374786: [lworld] C2: Missing asserts in parse3.cpp after merging JDK-8341411

Changes: https://git.openjdk.org/valhalla/pull/1982/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1982&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8374786
  Stats: 4 lines in 1 file changed: 4 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/valhalla/pull/1982.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1982/head:pull/1982

PR: https://git.openjdk.org/valhalla/pull/1982