RFR(S): 8189425: Minor updates in support of closed changes

[Erik Gahlin]

Hi,

Could I have a review of this change that will adjust an assertion and 
remove a lock associated with JFR.

Webrev:
http://cr.openjdk.java.net/~egahlin/8189425_0

Bug:
https://bugs.openjdk.java.net/browse/JDK-8189425

Thanks
Erik