Previously, the Definition class was used both for type inference and factory construction (if factoryService was absent). This is fine for cases where classes create instances of themselves (e.g. getInstance() or create()), but leads to ambiguity when we have a separate factory class.
In the dumped PHP class, we must use get() and not get*Service() methods to get services.
That's because all calls must be managed by get(). From the outside, you can call
get*Service() because as they are protected, they are caught by the __call() method;
which is not the case obviously when it is used internally.
If not, if you override a service with set(), this won't work when a service
depends on this one (the default one will still be used).
