Language tests updated to use const instead of final.

tests/language/string_interpolate_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 testing string interpolation.
 
 
 class WhatchamaCallIt {
   WhatchamaCallIt() { }
 
   String foo() {
     // Test $this and Field name is defined in subclass.
     return "$this and $name";
   }
 }
 
 class ThingamaBob extends WhatchamaCallIt {
   ThingamaBob(String s) : super(), name = s { }
   String name;
   toString() => "Hansel";
 }
 
 class StringInterpolateTest {
 
-  static final String A = "svin";
-  static final String B = "hest";
-  static final int N = 1 + 1;
+  static const String A = "svin";
+  static const String B = "hest";
+  static const int N = 1 + 1;
   static String Printers;
   static String AAR_Printers;
 
   static testMain() {
     Printers = "Printers: $A and $B";
     AAR_Printers  = "AAR has $N $Printers.";
 
     var x = 1;
     var s = "eins und \$x macht zwei.";
     print(s);
@@ skipping 17 matching lines @@
 
     var t = new ThingamaBob("Gretel");
     print(t.foo());
     Expect.equals(t.foo(), "Hansel and Gretel");
   }
 }
 
 main() {
   StringInterpolateTest.testMain();
 }