A smaller GC benchmark

[Craig Black]

> All of this would allow for a moving GC, but the GC would still be 
> somewhat conservative because type information would still not be 
> available for the stack (unless the app contained debug information, 
> perhaps).

Is there a way to provide type information for the stack without hindering 
performance too badly?  Obviously it will be better if the GC has as much 
information as possible.

-Craig