RFR(XS): JDK-8159328 [TESTBUG] ProblematicFrameTest.java throws an exception (due to trying to access Unsafe) but still passes

[George Triantafillou]

Please review this small change to fix a test failure in 
ProblematicFrameTest.java

JBS: https://bugs.openjdk.java.net/browse/JDK-8159328
Open webrev: http://cr.openjdk.java.net/~gtriantafill/8159328/webrev/ 
<http://cr.openjdk.java.net/%7Egtriantafill/8159328/webrev/>

Tested locally on Linux.

-George