RFR: 8011697(ScriptEngine "js" randomly means either "rhino" or "nashorn", but should instead select one)

[Srinivas Dama]

Hi,

Please review http://cr.openjdk.java.net/~sdama/8011697/webrev.00/ 
for https://bugs.openjdk.java.net/browse/JDK-8011697

Fix is to make sure ScriptEngineManager always returns a particular engine on 
all platforms consistently.

Regards,
Srinivas