Change new List(n) to return fixed length list.

tests/corelib/list_growable_test.dart

Index: tests/corelib/list_growable_test.dart
diff --git a/tests/corelib/list_growable_test.dart b/tests/corelib/list_growable_test.dart
index 616b4506259b2666d60567bfe14cc215aa682b35..3c0dab064901c3f98b2f77e13691fd4606c1f7d8 100644
--- a/tests/corelib/list_growable_test.dart
+++ b/tests/corelib/list_growable_test.dart
@@ -12,7 +12,7 @@ main() {
   Expect.equals(0, a.length);
   Expect.throws(() => a[0], (e) => e is RangeError);
 
-  a = new List(42);
+  a = new List(42).toList(growable: true);
   Expect.equals(42, a.length);
   a.add(499);
   Expect.equals(43, a.length);
@@ -22,7 +22,7 @@ main() {
   Expect.equals(0, a.length);
   Expect.throws(() => a[0], (e) => e is RangeError);
 
-  a = new List<int>(42);
+  a = new List<int>(42).toList(growable: true);
   Expect.equals(42, a.length);
   a.add(499);
   Expect.equals(43, a.length);