Language tests updated to use const instead of final.

tests/language/string_interpolation8_test.dart

Index: tests/language/string_interpolation8_test.dart
diff --git a/tests/language/string_interpolation8_test.dart b/tests/language/string_interpolation8_test.dart
index f4633151fbdea62c738f3b1158778d4d3d01c993..8999dafa8354f15b729bd19bc16dac32c0bd4ba8 100644
--- a/tests/language/string_interpolation8_test.dart
+++ b/tests/language/string_interpolation8_test.dart
@@ -2,11 +2,11 @@
 // 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.
 //
-// Allow assignment of string interpolation to a static final field
+// Allow assignment of string interpolation to a static const field
 
 class A {
-  static final x = 1;
-  static final y = "Two is greater than ${x}";
+  static const x = 1;
+  static const y = "Two is greater than ${x}";
 }
 
 main() {