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

tests/language/incr_op_test.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 // Dart test program for testing increment operator.
 
 class A {
   static var yy;
   static set y(v) {
     yy = v;
   }
@@ skipping 42 matching lines @@
     Expect.equals(57, A.y);
     Expect.equals(56, --A.y);
 
     IncrOpTest.y = 55;
     Expect.equals(55, IncrOpTest.y++);
     Expect.equals(56, IncrOpTest.y);
     Expect.equals(57, ++IncrOpTest.y);
     Expect.equals(57, IncrOpTest.y);
     Expect.equals(56, --IncrOpTest.y);
 
-    var list = new List.fixedLength(4);
+    var list = new List(4);
     for (int i = 0; i < list.length; i++) {
       list[i] = i;
     }
     for (int i = 0; i < list.length; i++) {
       list[i]++;
     }
     for (int i = 0; i < list.length; i++) {
       Expect.equals(i + 1, list[i]);
       ++list[i];
     }
     Expect.equals(1 + 2, list[1]);
     Expect.equals(1 + 2, list[1]--);
     Expect.equals(1 + 1, list[1]);
     Expect.equals(1 + 0, --list[1]);
   }
 }
 
 main() {
   IncrOpTest.testMain();
 }