Strong mode cleaning of many dart2js tests.

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/commandline_options.dart';
@@ skipping 95 matching lines @@
         if (!messageFound && checkMessage(message)) {
           messageFound = true;
         } else {
           unexpectedMessages.add(message);
         }
       }
       Expect.isTrue(
           messageFound,
           '${template.kind}} does not match any in\n '
           '${messages.join('\n ')}');
-      var reporter = compiler.reporter;
+      dynamic reporter = compiler.reporter;
       Expect.isFalse(reporter.hasCrashed);
       if (!unexpectedMessages.isEmpty) {
         for (CollectedMessage message in unexpectedMessages) {
           print("Unexpected message: $message");
         }
         if (!kindsWithExtraMessages.contains(template.kind)) {
           // Try changing the error reporting logic before adding an exception
           // to [kindsWithExtraMessages].
           throw 'Unexpected messages found.';
         }
@@ skipping 14 matching lines @@
           .isTrue(!pendingStuff || kindsWithPendingClasses.contains(template));
 
       if (!pendingStuff) {
         // If there is pending stuff, or the compiler was cancelled, we
         // shouldn't reuse the compiler.
         cachedCompiler = compiler;
       }
     });
   }).then((_) => cachedCompiler);
 }