[lworld] A couple of cleanups to Unified class file generation scheme

(1) com.sun.tools.javac.code.Printer#visitClassType should protect against missing class files in the manner of how com.sun.tools.javac.code.Type.ClassType#toString wraps the calls to isReferenceProjection()

(2) In com.sun.tools.javac.comp.Lower#access(com.sun.tools.javac.code.Symbol, com.sun.tools.javac.tree.JCTree.JCExpression, com.sun.tools.javac.tree.JCTree.JCExpression, boolean)

the code block:

if (requireReferenceProjection) {
       flatname = flatname.append('$', names.ref);
}

should be invoked only for the case where we generate bifurcated classes