Remove EarlyBinder::{try_fold_with,visit_with}.

For most types the default impls of these methods are good enough, and
`EarlyBinder` is one such type.

Author: nnethercote

compiler/rustc_middle/src/ty/structural_impls.rs

@@ -868,17 +868,9 @@ impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for ty::EarlyBinder<T> {
         self.try_map_bound(|ty| ty.try_fold_with(folder))
     }
 
-    fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
-        self.try_map_bound(|ty| ty.try_fold_with(folder))
-    }
-
     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
         self.as_ref().0.visit_with(visitor)
     }
-
-    fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
-        self.as_ref().0.visit_with(visitor)
-    }
 }
 
 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for ty::Binder<'tcx, T> {