[9-dev] RfR: JDK-8132743: Move netscape.javascript package from jdk.plugin to new module

[David DeHaven]

JBS Issue:
https://bugs.openjdk.java.net/browse/JDK-8132743

Code review:
http://cr.openjdk.java.net/~ddehaven/8132743/webrev.0/

Summary:
- Moved netscape.javascript.{JSObject,JSException} from closed source plugin to jdk
- Convert package.html to package-info.java
- Cleaned up Javadoc somewhat
- Removed long deprecated (and unused) methods from JSException (that had been documented publicly, in case anyone is paying attention)

Background:
The netscape.javascript package has been used by Applets running in web browsers to gain access to the JavaScript engine running in the browser for a very long time. Originally created by Netscape, it has become the de facto standard for communication between code running in a JVM and various JavaScript engines. It has also been adopted by other components such as JavaFX that now rely on its continued existence in the Java runtime so it make sense to migrate it from the plugin to a well known location.

I had to put the module in the boot modules as the plugin is currently loaded in the boot loader. This will change when Jigsaw M3 is integrated, the ultimate intention is for this to reside in the ext loader.

-DrD-