'a<T>::foo' is reserved if 'a' is a simple name and can be resolved as an expression
(this can be extended to 'a.b.c<T>::foo' case, although that is rather hard to implement using PSI).
'a?::foo' is reserved if 'a' can be resolved as an expression.
Previous resolution sequence (static scope, nested classes scope, receiver) and
a check against type parameters only made sense when there's a type, not an
expression, on the LHS of a callable reference. Also TransientReceiver is
incorrect in such case because private-to-this visibility check only works for
ExpressionReceiver values
In the expression "Runnable::run" we were resolving the left-hand side to the
SAM constructor of Runnable. Now we detect this situation, ignore the result of
such resolution, and continue resolving the LHS as a type
Alexander Udalov