Webrev for 6972759

[Bill Pittore]

Webrev for fix for 6972759 is at 
http://cr.openjdk.java.net/~bpittore/6972759/webrev.00/

This bug has to do with single stepping after hitting an exception 
breakpoint. The short story is that JVMTI maintains some thread state 
information that was not updated correctly if a frame was popped off the 
stack. When you pop a frame the exception state should go back to 
_exception_detected=false. Otherwise when MethodExit event is sent at 
some time in the future the 'was_popped_by_exception' flag will be set 
and the agent receiving the event may not re-enable single stepping 
properly. This problem will also affect ForceEarlyReturn code. Hacked up 
a couple of existing nsk/jvmti tests to issue the necessary sequence of 
JVMTI calls/events in order to test original bug and this fix.

bill