RFR: 8270014: Add scoped objects for g1 young gc verification and young gc internal timing [v2]

[Thomas Schatzl]

> Hi all,
> 
>   can I get reviews for some further cleanup of the young collection code:
> - adding some more scoped objects (verification, gc pause timing)
> - some naming, minor related code movement
> 
> Thanks,
>   Thomas

Thomas Schatzl has updated the pull request incrementally with one additional commit since the last revision:

  Fix test because of slightly different log message order

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/4768/files
  - new: https://git.openjdk.java.net/jdk/pull/4768/files/c321d385..7730aa6d

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=4768&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=4768&range=00-01

  Stats: 8 lines in 2 files changed: 1 ins; 2 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4768.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4768/head:pull/4768

PR: https://git.openjdk.java.net/jdk/pull/4768