JFR: Clean up jdk.jfr.internal.RepositoryChunk

[Erik Gahlin]

Hi,

Could I have a review of a fix that cleans up the RepositoryChunk class.

Bug:
https://bugs.openjdk.java.net/browse/JDK-8244463

Webrev:
http://cr.openjdk.java.net/~egahlin/8244463/

Testing: jdk/jdk/jfr

Thanks
Erik