Use List instead of Link in the type system.

tests/compiler/dart2js/link_test.dart

Index: tests/compiler/dart2js/link_test.dart
diff --git a/tests/compiler/dart2js/link_test.dart b/tests/compiler/dart2js/link_test.dart
index 55d6ae3465e2d5c50490e800d7735f73f408719b..37c7ce53094837fd692cd5c545120b67b5f02518 100644
--- a/tests/compiler/dart2js/link_test.dart
+++ b/tests/compiler/dart2js/link_test.dart
@@ -4,7 +4,7 @@
 
 import "package:expect/expect.dart";
 import '../../../sdk/lib/_internal/compiler/implementation/util/util.dart';
-import '../../../sdk/lib/_internal/compiler/implementation/util/util_implementation.dart';
+import 'link_helper.dart';
 
 main() {
   test(const Link<Comparable>().prepend('three').prepend(2).prepend('one'),
@@ -13,20 +13,9 @@ main() {
        [1, 'two', 3]);
   test(const Link<String>().prepend('single'), ['single']);
   test(const Link(), []);
-  testFromList([]);
-  testFromList([0]);
-  testFromList([0, 1]);
-  testFromList([0, 1, 2]);
-  testFromList([0, 1, 2, 3]);
-  testFromList([0, 1, 2, 3, 4]);
-  testFromList([0, 1, 2, 3, 4, 5]);
   testSkip();
 }
 
-testFromList(List list) {
-  test(new Link.fromList(list), list);
-}
-
 test(Link link, List list) {
   Expect.equals(list.isEmpty, link.isEmpty);
   int i = 0;
@@ -48,7 +37,7 @@ test(Link link, List list) {
 }
 
 testSkip() {
-  var nonEmptyLink = new Link.fromList([0, 1, 2, 3, 4, 5]);
+  var nonEmptyLink = LinkFromList([0, 1, 2, 3, 4, 5]);
   for (int i = 0 ; i < 5; i++) {
     var link = nonEmptyLink.skip(i);
     Expect.isFalse(link.isEmpty);