Fix #13140: Early/Late Bound related ICEs.

The problem was that we need to apply the substitution, so that the
formal lifetime parameters get replaced with (unifiable)
free-lifetimes that can actually be fed into the constraint solver.

Also, refactor code os that substitution for `check_item` and
`check_method`, moving both down the control flow into `check_bare_fn`.

----

Finally, there was another (similar) spot where we needed to
substitute early-bound lifetimes when invoking an object method of a
trait.

src/librustc/middle/typeck/check/method.rs

@@ -263,6 +263,7 @@ fn construct_transformed_self_ty_for_object(
             let transformed_self_ty = *method_ty.fty.sig.inputs.get(0);
             match ty::get(transformed_self_ty).sty {
                 ty::ty_rptr(r, mt) => { // must be SelfRegion
+                    let r = r.subst(tcx, &substs); // handle Early-Bound lifetime
                     ty::mk_trait(tcx, trait_def_id, substs,
                                  RegionTraitStore(r), mt.mutbl,
                                  ty::EmptyBuiltinBounds())

src/librustc/middle/typeck/check/mod.rs

@@ -329,6 +329,10 @@ fn check_bare_fn(ccx: &CrateCtxt,
                  id: ast::NodeId,
                  fty: ty::t,
                  param_env: ty::ParameterEnvironment) {
+    // Compute the fty from point of view of inside fn
+    // (replace any type-scheme with a type)
+    let fty = fty.subst(ccx.tcx, &param_env.free_substs);
+
     match ty::get(fty).sty {
         ty::ty_bare_fn(ref fn_ty) => {
             let inh = Inherited::new(ccx.tcx, param_env);
@@ -678,9 +682,7 @@ fn check_method_body(ccx: &CrateCtxt,
             method_generics.region_param_defs(),
             method.body.id);
 
-    // Compute the fty from point of view of inside fn
     let fty = ty::node_id_to_type(ccx.tcx, method.id);
-    let fty = fty.subst(ccx.tcx, &param_env.free_substs);
 
     check_bare_fn(ccx, method.decl, method.body, method.id, fty, param_env);
 }