Propagate the information that a monomorphic prototype failure has...

Propagate the information that a monomorphic prototype failure has
occured.  After a monomorphic prototype failure has been detected,
other monomorphic inline caches for the same type will have a code
object in the map's code cache which is not the current target.  We
recognize this case and use the code object that is in the cache
instead of going megamorphic.


Committed: http://code.google.com/p/v8/source/detail?r=331