[Pharo-project] Little fix for #4697

In inbox: Name: Tools-MikeRoberts.658 Issue: 4697 -Fix to OrderedCollectionInspector that fails #fieldList on OrderedCollections that are not fully formed. ---- I did a little fix for this bug, that prevents the debugger stepping into OrderedCollection new. I mention this to folks working on tools because it is an interesting edge case. If you specialise an inspector for a particular class, for example, you have to handle the case where the object is not fully formed. e.g right after basicNew, or in the middle of some initialisation. It failed for the debugger, because it relies on embedding an inspector for the receiver (bottom left) panel. So i guess this edge case is subtle... cheers, Mike