8144979: Context.fromClass should catch exception from Class.getClassLoader call

[Sundararajan Athijegannathan]

This is in response to 
http://mail.openjdk.java.net/pipermail/nashorn-dev/2015-December/005699.html

Found the root cause of difference in behavior between "jake/jigsaw" and 
"jdk9-dev".
Filed: https://bugs.openjdk.java.net/browse/JDK-8145070

Thanks,
-Sundar