Strong mode cleaning of many dart2js tests.

tests/compiler/dart2js/dart2js_batch2_test.dart

Index: tests/compiler/dart2js/dart2js_batch2_test.dart
diff --git a/tests/compiler/dart2js/dart2js_batch2_test.dart b/tests/compiler/dart2js/dart2js_batch2_test.dart
index 9aeec1d52cae2a4e3d150c972abe6197c56c28bc..0fac8aa1a6d17d843f99eb6a74f4aaa876a5a479 100644
--- a/tests/compiler/dart2js/dart2js_batch2_test.dart
+++ b/tests/compiler/dart2js/dart2js_batch2_test.dart
@@ -67,14 +67,11 @@ Future runTests(Process process) {
   Future<String> errorOut = process.stderr.transform(UTF8.decoder).join();
   return Future.wait([output, errorOut]).then((result) {
     String stdoutOutput = result[0];
-    String stderrOutput = result[1];
-
     Expect.isFalse(stdoutOutput.contains("crashed"));
   });
 }
 
 void main() {
-  var tmpDir;
   asyncTest(() {
     return setup().then(launchDart2Js).then(runTests).whenComplete(cleanUp);
   });