RFR: 8286870: Memory leak with RepeatCompilation

[Tobias Hartmann]

While using `RepeatCompilation` in combination with replay compilation and stress options to reproduce an intermittent issue, I noticed that it does not free the compiler thread arena after each compilation, leading to a (temporary) memory leak and out of memory errors. For example, each compilation of [JDK-8280696](https://bugs.openjdk.java.net/browse/JDK-8280696) allocates an additional 1218 kB.

The fix is to simply add a `ResourceMark` in the loop.

Thanks,
Tobias

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Commit messages:
 - 8286870: Memory leak with RepeatCompilation

Changes: https://git.openjdk.java.net/jdk/pull/8744/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8744&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8286870
  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8744.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8744/head:pull/8744

PR: https://git.openjdk.java.net/jdk/pull/8744