[8u60] 8072002: The spec on javax.script.Compilable contains a typo and confusing inconsistency

[A. Sundararajan]

Please approve.


Bug: https://bugs.openjdk.java.net/browse/JDK-8072002
jdk9 review thread: 
http://mail.openjdk.java.net/pipermail/core-libs-dev/2015-May/033552.html
jdk8u-dev webrev: http://cr.openjdk.java.net/~sundar/8072002/8u60/webrev.00/

Backported 'as is' except for the modular source code layout difference.

Thanks,
-Sundar