swift

4fbb3ec6 - [GSB] Resolve nested types by looking into superclass constraints.

[GSB] Resolve nested types by looking into superclass constraints. This was previously handled very late, by the type checker, which led to weird ordering dependencies and meant that we could end up with well-formed code where the GSB was left with unresolved types. We want such states to never exist, so make sure we can resolve everything in the GSB.