cmd/compile/internal/types2: remove some unnecessary loading/expansion of Named types

This is a clean port of CL 349409 from go/types to types2.

Change-Id: I2deb9ce46e6dcda736fda2169912c02163930d7d
Reviewed-on: https://go-review.googlesource.com/c/go/+/349991
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
diff --git a/src/cmd/compile/internal/types2/predicates.go b/src/cmd/compile/internal/types2/predicates.go
index 473d226..aa797fc 100644
--- a/src/cmd/compile/internal/types2/predicates.go
+++ b/src/cmd/compile/internal/types2/predicates.go
@@ -302,9 +302,6 @@
 		// Two named types are identical if their type names originate
 		// in the same type declaration.
 		if y, ok := y.(*Named); ok {
-			x.expand(nil)
-			y.expand(nil)
-
 			xargs := x.TypeArgs().list()
 			yargs := y.TypeArgs().list()
 
diff --git a/src/cmd/compile/internal/types2/unify.go b/src/cmd/compile/internal/types2/unify.go
index a1e5b36..bb69f0d 100644
--- a/src/cmd/compile/internal/types2/unify.go
+++ b/src/cmd/compile/internal/types2/unify.go
@@ -428,9 +428,6 @@
 
 	case *Named:
 		if y, ok := y.(*Named); ok {
-			x.expand(nil)
-			y.expand(nil)
-
 			xargs := x.targs.list()
 			yargs := y.targs.list()