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

tests/language/optimization_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.
 // Test various optimizations and deoptimizations of optimizing compiler..
 
 addThem(a, b) {
   return a + b;
 }
 
 isItInt(a) {
@@ skipping 45 matching lines @@
   for (int i = -500; i < 500; i++) {
     var r = doNeg(i);
     var p = doNeg(r);
     Expect.equals(i, p);
   }
   var maxSmi = (1 << 30) - 1;
   Expect.equals(maxSmi, doNeg(doNeg(maxSmi)));
   // Deoptimize because of overflow.
   var minInt = -(1 << 30);
   Expect.equals(minInt, doNeg(doNeg(minInt)));
-  
+
   for (int i = 0; i < 1000; i++) {
     Expect.equals(false, doNot(true));
     Expect.equals(true, doNot(doNot(true)));
   }
   for (int i = 0; i < 1000; i++) {
     Expect.equals(-57, doBitNot(56));
     Expect.equals(55, doBitNot(-56));
   }
 
   for (int i = 0; i < 2000; i++) {
     Expect.equals(-2.2, doNeg2(2.2));
   }
   // Deoptimize.
   Expect.equals(-5, doNeg2(5));
 
-  var fixed = new List.fixedLength(10);
+  var fixed = new List(10);
   var growable = [1, 2, 3, 4, 5];
 
   for (int i = 0; i < 2000; i++) {
     doStore1(fixed, 7);
     Expect.equals(7, fixed[1]);
     doStore2(growable, 12);
     Expect.equals(12, growable[2]);
   }
 
   // Deoptimize.
   doStore1(growable, 8);
   Expect.equals(8, growable[1]);
   doStore2(fixed, 101);
   Expect.equals(101, fixed[2]);
 }