#1264 Uninitialized trait method

| deferred |
deferred := JQuery current Deferred new.
[deferred resolve: 'ok'] valueWithTimeout: 1000.
deferred promise then: []

Executing ``` | deferred | deferred := JQuery current Deferred new. [deferred resolve: 'ok'] valueWithTimeout: 1000. deferred promise then: [] ``` raises the error: nil does not understand #applyTo:arguments: This is due to the TThenable>>#then: not being initialized, that is instantiateFn not being used to set method.fn. It seems to be related to commit d8ba5d3b0fbc277816b6ada3a284285332b63055 The example uses a jquery deferred, but the problem is common to other thenables.