Enabled fully-functional interfaces. As part of this feature, moved
built-in classes Class, int and uint back to AS3.js, because they are
needed for special cases in "is" type check. More closely resembles
AS3 semantics of "is" by converting primitives to Objects first and
by checking int and uint (similar to old Runtime).
Changes some spaces in code genration, resulting in all test files
to be touched.