swift234

Implement filtering of overload sets based on argument and destination
types. Use this simple overload resolution scheme in both type
checking and type coercion, simplifying both code paths a bit.

There is one significant semantic change here: we allow overload
resolution to operate on (structured) dependent arguments, which
allows for more overload filtering before we come in with the type
coercion hammer. For example, we can now properly type-check

  var x : int32;
  x + 0;



Swift SVN r1310