RFR: 8035618 : Four api/org_omg/CORBA TCK tests fail under plugin only

[Seán Coffey]

Looking to push a fix to JDK 8. A CORBA issue was discovered during 
TCK-Plugin testing. The NPE seen should be handled and the 
defaultPresentationManager should be returned where necessary.

Bug ID : https://bugs.openjdk.java.net/browse/JDK-8035618
webrev : http://cr.openjdk.java.net/~coffeys/webrev.8035618/webrev/
regards,
Sean.