SI-7517 type constructors too eagerly normalized.

I think 403eadd0f1 was largely a symptomatic remedy (not that
we shouldn't harden against such outcomes) and that this commit
gets closer to the root causes. The unanticipated change to
test/files/run/t6113.check is like a cry of support from the jury box.

  -Foo[[X](Int, X)]
 +Foo[AnyRef{type l[X] = (Int, X)}#l]

We should continue to look upon calls to normalize with grave suspicion.