Associated objects are actively dangerous there because they’re non-isolated
actor state, and it’s “new” code wher no backward compatibility concerns that
make it more difficult to ban this on other forms of classes.
rdar://69769048
refcounting and take advantage of it.
Also, set the Swift1 flag in classes we generate.
Also, initialize a global cache of the non-pointer-isa
mask and use that instead of object_getClass, at least
within the runtime.
Also, centralize the runtime on a _swift_getSuperclass
function and make that use a direct access while we
await word from Greg on the desired ABI requirements.
Swift SVN r21077
