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

tests/language/inst_field_initializer1_negative_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.
 // Catch illegal access to 'this' in initalized instance fields.
 
 
 class A {
   A() {}
   int x = 5;
-  int arr = new List.fixedLength(x);  // Illegal access to 'this'.
+  int arr = new List(x);  // Illegal access to 'this'.
                           // Also not a compile const expression.
 }
 
 void main() {
   var foo = new A();
 }