Add a compile time error for non-static const fields

tests/language/const_instance_field_test.dart

 // Copyright (c) 2014, 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.
-library pop_pop_win.game_web;
 
-import 'platform_web.dart';
-import 'package:pop_pop_win/pop_pop_win.dart';
+// Test that const instance fields are compile-time errors.
+
+class C {
+  const field = 0; /// 01: compile-time error
+}
 
 void main() {
-  startGame(new PlatformWeb());
-}
+  new C();
+}