RFR 8144189: Turn off Tiered compilation for nashorn test262parallel test run

[Sundararajan Athijegannathan]

Please review http://cr.openjdk.java.net/~sundar/8144189/ for 
https://bugs.openjdk.java.net/browse/JDK-8144189

Piggybacking to remove excluded list for test262 tests and also to make 
test exclusion work properly [though there are no tests excluded now]

Thanks,
-Sundar