Use List instead of Link in the type system.

tests/compiler/dart2js/subtype_test.dart

Index: tests/compiler/dart2js/subtype_test.dart
diff --git a/tests/compiler/dart2js/subtype_test.dart b/tests/compiler/dart2js/subtype_test.dart
index 054df32104615c09944d6117a20f5da0e41af02e..45179bdb94b52e51d4d522883f4a256dce0fcf42 100644
--- a/tests/compiler/dart2js/subtype_test.dart
+++ b/tests/compiler/dart2js/subtype_test.dart
@@ -557,32 +557,32 @@ void testTypeVariableSubtype() {
     }
 
     ClassElement A = env.getElement('A');
-    TypeVariableType A_T = A.thisType.typeArguments.head;
+    TypeVariableType A_T = A.thisType.typeArguments[0];
     ClassElement B = env.getElement('B');
-    TypeVariableType B_T = B.thisType.typeArguments.head;
+    TypeVariableType B_T = B.thisType.typeArguments[0];
     ClassElement C = env.getElement('C');
-    TypeVariableType C_T = C.thisType.typeArguments.head;
+    TypeVariableType C_T = C.thisType.typeArguments[0];
     ClassElement D = env.getElement('D');
-    TypeVariableType D_T = D.thisType.typeArguments.head;
+    TypeVariableType D_T = D.thisType.typeArguments[0];
     ClassElement E = env.getElement('E');
-    TypeVariableType E_T = E.thisType.typeArguments.head;
-    TypeVariableType E_S = E.thisType.typeArguments.tail.head;
+    TypeVariableType E_T = E.thisType.typeArguments[0];
+    TypeVariableType E_S = E.thisType.typeArguments[1];
     ClassElement F = env.getElement('F');
-    TypeVariableType F_T = F.thisType.typeArguments.head;
-    TypeVariableType F_S = F.thisType.typeArguments.tail.head;
+    TypeVariableType F_T = F.thisType.typeArguments[0];
+    TypeVariableType F_S = F.thisType.typeArguments[1];
     ClassElement G = env.getElement('G');
-    TypeVariableType G_T = G.thisType.typeArguments.head;
+    TypeVariableType G_T = G.thisType.typeArguments[0];
     ClassElement H = env.getElement('H');
-    TypeVariableType H_T = H.thisType.typeArguments.head;
-    TypeVariableType H_S = H.thisType.typeArguments.tail.head;
+    TypeVariableType H_T = H.thisType.typeArguments[0];
+    TypeVariableType H_S = H.thisType.typeArguments[1];
     ClassElement I = env.getElement('I');
-    TypeVariableType I_T = I.thisType.typeArguments.head;
-    TypeVariableType I_S = I.thisType.typeArguments.tail.head;
-    TypeVariableType I_U = I.thisType.typeArguments.tail.tail.head;
+    TypeVariableType I_T = I.thisType.typeArguments[0];
+    TypeVariableType I_S = I.thisType.typeArguments[1];
+    TypeVariableType I_U = I.thisType.typeArguments[2];
     ClassElement J = env.getElement('J');
-    TypeVariableType J_T = J.thisType.typeArguments.head;
-    TypeVariableType J_S = J.thisType.typeArguments.tail.head;
-    TypeVariableType J_U = J.thisType.typeArguments.tail.tail.head;
+    TypeVariableType J_T = J.thisType.typeArguments[0];
+    TypeVariableType J_S = J.thisType.typeArguments[1];
+    TypeVariableType J_U = J.thisType.typeArguments[2];
 
     DartType Object_ = env['Object'];
     DartType num_ = env['num'];