RFR: 8348887: Create IR framework test for JDK-8347997

[Marc Chevalier]

As the ticket says:
> Create IR framework test which checks that allocations are eliminated in the regression test included in [JDK-8347997](https://bugs.openjdk.org/browse/JDK-8347997) fix.

So here it is! We can see that in case of inlining, indeed, no allocation happens. The second part is some sanity check to emphasize the difference: of course, there is an allocation without inlining. The benefit of this second part is arguable. From my point of view, it's mostly to point out the difference to a future reader. But yes, there is nothing very surprising.

Thanks,
Marc

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Commit messages:
 - Turn TestContinuationPinningAndEA into IR test

Changes: https://git.openjdk.org/jdk/pull/24328/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24328&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8348887
  Stats: 136 lines in 1 file changed: 136 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/24328.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24328/head:pull/24328

PR: https://git.openjdk.org/jdk/pull/24328