Necessary to resolve any type arguments in a ref to a parameterized
iface. This meant that, for example:
class A implements B<int> { ...
didn't work before, because the "int" in B's argument wasn't getting
visited, and thus wasn't getting resolved. Now it works.
Partially addresses Issue #2288, but I also want to check that class
ty params can appear as the type arguments to ifaces (for example,
class A<T> implements B<T> {...
should work.)