RFR 8206086: [Graal] JDI tests fail with com.sun.jdi.ObjectCollectedException

[Daniil Titov]

Please review the changes that fix 4 JDI tests that fail when running with Graal.

The problem here is that in some cases by the time the test decides whether the JDI event should be saved for further analysis the object this event refers to might be already collected in the debuggee VM. The fix ensures that if this happens then ObjectCollectedException is gracefully handled and the event is skipped.

Bug: https://bugs.openjdk.java.net/browse/JDK-8206086 
Webrev: http://cr.openjdk.java.net/~dtitov/8206086/webrev.001/

Thanks!

--Daniil