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.
And String.length as well.
This is done for JVM interoperability: java.lang.CharSequence is an open class
and has a function 'length()' which should be implemented in subclasses
somehow.
A minor unexpected effect of this is that String.length() is now a compile-time
constant (it wasn't such as a property because properties are not supported in
compile-time constant evaluation)
#KT-3571 Fixed
