It's need to add synthetic argument (of type that user can't use)
to constructors with default arguments to avoid clashing with
real user's constructor having the same set of parameters
and additional int's arguments.
There is a lot of changes about closures calculating and generating.
1. As classes can have more than one constructor each of them should
have closure arguments.
2. Captured variables set is the same for all of them.
3. Within constructors bodies/delegating calls closure parameters
should be accessed through method arguments because fields may be
not initialized yet.
Denis Zharkov