RFR: 8265330: G1: Fix comment in G1FullGCPrepareTask::G1CalculatePointersClosure

[Thomas Schatzl]

Hi all,

  can I have reviews for this trivial(?) comment update?

Thanks,
  Thomas

Testing: local compilation

-------------

Commit messages:
 - Fix comment

Changes: https://git.openjdk.java.net/jdk/pull/3538/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=3538&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8265330
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3538.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3538/head:pull/3538

PR: https://git.openjdk.java.net/jdk/pull/3538