dart2js: Fix check for support of reflection.

pkg/compiler/lib/src/warnings.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.
 
 part of dart2js;
 
 const DONT_KNOW_HOW_TO_FIX = "Computer says no!";
 
 /**
  * The messages in this file should meet the following guide lines:
@@ skipping 2506 matching lines @@
 *
 * You can disable this message by using the --enable-experimental-mirrors
 * command-line flag.
 *
 * To learn what to do next, please visit:
 *    http://dartlang.org/dart2js-reflection
 ****************************************************************
 ''');
 
 
-  static const MessageKind MIRRORS_LIBRARY_NEW_EMITTER =
+  static const MessageKind MIRRORS_LIBRARY_NOT_SUPPORT_BY_BACKEND =
       const MessageKind(
-          "dart:mirrors library is not supported when using the new emitter "
-            "(DART_VM_OPTIONS='-Ddart2js.use.new.emitter=true')");
+          "dart:mirrors library is not supported when using this backend.");

[Johnni Winther, 2015/07/16 18:14:29]

Which backend? Can you provide more info and maybe howToFix to the user?

[floitsch, 2015/07/17 13:16:19]

I wondered. (After all I removed the old one).
I think the complexity is not worth the effort:
- the emitter knows if it supports reflection.
- the choice of how the emitter was selected is not completely clear. Currently
it's a compile-time constant. It should become a flag, and could also change
depending on different things (like using the startup-emitter for CSP
compilation if there is no reflection).

All in all, I expect this to be a rare problem.

 
   static const MessageKind CALL_NOT_SUPPORTED_ON_NATIVE_CLASS =
       const MessageKind(
           "Non-supported 'call' member on a native class, or a "
           "subclass of a native class.");
 
   static const MessageKind DIRECTLY_THROWING_NSM =
       const MessageKind(
           "This 'noSuchMethod' implementation is guaranteed to throw an "
           "exception. The generated code will be smaller if it is "
@@ skipping 70 matching lines @@
   static String convertToString(value) {
     if (value is ErrorToken) {
       // Shouldn't happen.
       return value.assertionMessage;
     } else if (value is Token) {
       value = value.value;
     }
     return '$value';
   }
 }