... in unspecified behavior.
When compiling with UBSan (-fsanitize=undefined), execution complains:
> runtime error: load of value 5, which is not a valid value for type 'nsSMState'
Since the machine states depend on every different charset's state
machine, it is not possible to simply extend the enum with more generic
values. Instead let's just make the state as an unsigned int value and
define the 3 generic states as constants.