4c1228276b
Tweak relations to no longer rely on `TypeTrace` Remove `At::trace`, and inline all of the `Trace::equate`,etc methods into `At`. The only nontrivial change is that we use `AliasTerm` to relate two unevaluated consts in the old-solver impl of `ConstEquate`, since `AliasTerm` does implement `ToTrace` and will relate the args structurally (shallowly). r? lcnr