Nestmates spec update

[Dan Smith]

At the August 3 meeting, we discussed revising the treatment of private method invocations, asking compilers to use 'invokevirtual' and 'invokeinterface' rather than 'invokespecial'. This allows us to leave 'invokespecial' untouched, rather than adding to its already-significant complexity.

See here for a proposed specification:
http://cr.openjdk.java.net/~dlsmith/private-access.html

The 'invokevirtual' calls were already supported, but in order to invoke private interface methods, we needed to enhance 'invokeinterface'. I thought the best way to accomplish this is to unify the selection process for 'invokevirtual' and 'invokeinterface' into a single algorithm. This also addresses some outstanding bugs and enhancement requests, as noted.

—Dan