JEP draft: Better-defined JVM class file validation

[Dan Smith]

Posted a new JEP draft, here:

http://openjdk.java.net/jeps/8267650

This is some preparatory work to allow us to more cleanly introduce the variety of new JVM features coming with primitive objects (JEP 401).

Most of the spec work is already done; you can browse the proposed spec changes here:
http://cr.openjdk.java.net/~dlsmith/8267650/8267650-20210603/specs/