It's done with similar constructions where possible trying to preserve
intended behavior.
Some usages are removed because they test exactly the feature that
we are going to drop soon.
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
Mikhail Glukhikh