test closed/javax/swing/JList/4908142/bug4908142.java failed intermittently with jdk7 and jdk8 on ubuntu

I can't reproduce the issues on OEL5.8 64 bit, Solaris 11 64 bit, but most likely it is a test bug

Reproduce 2 different failures:
1. sometimes test hangs, reproduced with jdk7b148, jdk8b92 (it can be due variables are not marked volatile and there is no call of Toolkit.realSync())
2. sometimes test failed with "java.lang.Error: The selected index should be "aad", but not ade", reproduced with jdk7u21b14 (it can be due there is no set auto delay for Robot and there is no call of Toolkit.realSync())