RFR: 8239793: 'jfr' tool should hide hidden frames

[Erik Gahlin]

Hi,

Could I have review of a fix that filters out hidden frames for the 
'jfr' tool?

Webrev:
http://cr.openjdk.java.net/~egahlin/8239793/

Bug:
https://bugs.openjdk.java.netbrowse/JDK-8239793

Testing:
jdk/jdk/jfr

Thanks
Erik