Remove ConstantExpression.value

tests/compiler/dart2js/message_kind_helper.dart

 // Copyright (c) 2013, 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 dart2js.test.message_kind_helper;
 
 import 'package:expect/expect.dart';
 import 'dart:async';
 
 import 'package:compiler/src/dart2jslib.dart' show
     Compiler,
     MessageKind;
+import 'package:compiler/src/dart_backend/dart_backend.dart' show
+    DartBackend;
 
 import 'memory_compiler.dart';
 
 const String ESCAPE_REGEXP = r'[[\]{}()*+?.\\^$|]';
 
 /// Most examples generate a single diagnostic.
 /// Add an exception here if a single diagnostic cannot be produced.
 /// However, consider that a single concise diagnostic is easier to understand,
 /// so try to change error reporting logic before adding an exception.
 final Set<MessageKind> kindsWithExtraMessages = new Set<MessageKind>.from([
@@ skipping 39 matching lines @@
                     "Example map must contain a 'main.dart' entry.");
     }
     List<String> messages = <String>[];
     void collect(Uri uri, int begin, int end, String message, kind) {
       if (kind.name == 'verbose info' || kind.name == 'info') {
         return;
       }
       messages.add(message);
     }
 
+    bool oldBackendIsDart;
+    if (cachedCompiler != null) {
+      oldBackendIsDart = cachedCompiler.backend is DartBackend;
+    }
+    bool newBackendIsDart = kind.options.contains('--output-type=dart');
+
     Compiler compiler = compilerFor(
         example,
         diagnosticHandler: collect,
         options: ['--analyze-only',
                   '--enable-experimental-mirrors']..addAll(kind.options),
-        cachedCompiler: cachedCompiler);
+        cachedCompiler:
+             // TODO(johnniwinther): Remove this restriction when constant
+             // values can be computed directly from the expressions.
+             oldBackendIsDart == newBackendIsDart ? cachedCompiler : null);
 
     return compiler.run(Uri.parse('memory:main.dart')).then((_) {
 
       Expect.isFalse(messages.isEmpty, 'No messages in """$example"""');
 
       String expectedText = !kind.hasHowToFix
           ? kind.template : '${kind.template}\n${kind.howToFix}';
       String pattern = expectedText.replaceAllMapped(
           new RegExp(ESCAPE_REGEXP), (m) => '\\${m[0]}');
       pattern = pattern.replaceAll(new RegExp(r'#\\\{[^}]*\\\}'), '.*');
@@ skipping 38 matching lines @@
       Expect.isTrue(!pendingStuff || kindsWithPendingClasses.contains(kind));
 
       if (!pendingStuff) {
         // If there is pending stuff, or the compiler was cancelled, we
         // shouldn't reuse the compiler.
         cachedCompiler = compiler;
       }
     });
   }).then((_) => cachedCompiler);
 }