instVarNames is not including instance variables coming from Stateful traits

[gcotelli]

For example, TextPresenter is using TSpecHaveWrappingScrollBars that includes a wrapScrollBars slot, but
TextPresenter superclass instSize >> 40
TextPresenter instSize >> 42 "Seems to be considered here, but:"
TextPresenter instVarNames -> #(#scrollValue)

This is breaking Fuel serialization because ClassDescritpion>>instanceVariableNamesDo: uses instSize to iterate over the variables returned by instVarName, so you get a SubscriptOutOfBounds error.

[jecisc]

Seems linked to #3546 and #3520

[MarcusDenker]

I adde a PR that we might consider: #4367

The idea is that #instVarnames should return #slots, not #localSlots.

[MarcusDenker]

This is now fixed