VMAccessController suggestion

Hi.

You probably know that currently java.security.VMAccessController.getStack() 
is unimplemented in SableVM, and this effectively disables any use of the 
java.security.AccessController+Permission based security framework (took me 
quite long to find that out).

I only found an old IRC log on that topic, which did not seem to have any 
result.

getStack() needs an array of the Class objects on the stack, and an array of 
String objects with the names of the functions.
Currently there is Java_gnu_classpath_VMStackWalker_fillContext which provides 
an array of classes (used by SecurityManager.getClassContext), and 
Java_java_lang_Throwable_nativeGetStackTraceList which provides a String list 
of some sort, but does _a lot_ more things (files, line numbers).

Am I missing something when I say that the VMStackWalker implementation can be 
used to obtain the Classes array for VMAccessController.getStack()?
If that is possible, I would suggest to add a native function like 
fillMethodNames to VMStackWalker (or move both to some other class? I would 
not, depends on your taste), which is as lightweight as fillContext, to 
obtain the method names, and use both in VMAccessController.getStack().

Marcel