swift234

Replace the constructor 'alllocates_this' attribute with an 'allocate-this' expression.

By splitting out the expression used to allocate 'this' (which exists
in the AST but cannot be written in the Swift language proper), we
make it possible to emit non-allocating constructors for imported
Objective-C classes, which are the only classes that have an
allocate-this expression.


Swift SVN r3558