RFR JDK-8215716: PopFrame() was unexpectedly done

[Alex Menkov]

Hi all,

please review a small fix for
https://bugs.openjdk.java.net/browse/JDK-8215716
webrev:
http://cr.openjdk.java.net/~amenkov/popframe004/webrev.01/

The failure is caused by race condition - main test thread calls 
PopFrame expecting that test thread is in the activeMethod method.
But logging (System.out.println call) is performed after main frame is 
notified that test thread is ready to be popped.

More general

--alex