Language tests updated to use const instead of final.

tests/language/compile_time_constant_d_test.dart

 // Copyright (c) 2012, 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.
 
 class A {
   final x;
   final y;
   final z;
   final t;
 
   const A(this.z, tt) : y = 499, t = tt, x = 3;
   const A.named(z, this.t) : y = 400 + z, this.z = z, x = 3;
   const A.named2(t, z, y, x) : x = t, y = z, z = y, t = x;
 
   toString() => "A $x $y $z $t";
 }
 
-final a1 = const A(99, 100);
-final a2 = const A.named(99, 100);
-final a3 = const A.named2(1, 2, 3, 4);
+const a1 = const A(99, 100);
+const a2 = const A.named(99, 100);
+const a3 = const A.named2(1, 2, 3, 4);
 
 main() {
   Expect.equals(3, a1.x);
   Expect.equals(499, a1.y);
   Expect.equals(99, a1.z);
   Expect.equals(100, a1.t);
   Expect.equals("A 3 499 99 100", a1.toString());
 
   Expect.isTrue(a1 === a2);
 
   Expect.equals(1, a3.x);
   Expect.equals(2, a3.y);
   Expect.equals(3, a3.z);
   Expect.equals(4, a3.t);
   Expect.equals("A 1 2 3 4", a3.toString());
 }