Review request for JDK-8023373

[Attila Szegedi]

Please review JDK-8023373 at http://cr.openjdk.java.net/~attila/8023373/webrev.00

Much of the change is just refactoring -- we already had code for emitting super calls, as overridable methods that did not have an overridde specified by an adapter instance had to delegate to the super call, so the change really was to extract it into emitSuperCall() method, which in turn made generateSuperMethod() really trivial. The rest of the changes in generateMethod() are really just  refactorings, and moving some code around (e.g. definition of nextLocalVar was moved closer to the point where it was used). 
 
Thanks,
  Attila.