RFR: 8356779: IGV: dump the index of the SafePointNode containing the current JVMS during parsing

[Saranya Natarajan]

This PR prints index of the SafePointNode containing the current JVMS during parsing in IGV. As stated in JBS the reason for this is that there are a lot of nodes during parsing, it would be nice to know what are the current nodes in the local slots or in the stack when looking at a graph.

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Commit messages:
 - initial fix

Changes: https://git.openjdk.org/jdk/pull/27083/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27083&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8356779
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/27083.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27083/head:pull/27083

PR: https://git.openjdk.org/jdk/pull/27083