Fix simulator bitrot

These changes enable the StackInterpreterSimulator to load a Pharo 1.2 image, until it hits issues with the BalloonEngine.

The magic expression is:
```Smalltalk
| sim |
InterpreterStackPage initialize.
StackInterpreterSimulator initializeWithOptions: Dictionary new.
sim :=  StackInterpreterSimulator new.
sim openOn: 'Pharo-1.2.1.image'.
sim openAsMorph.
[ sim run ] fork.
```