Strong mode cleaning of many dart2js tests.

tests/compiler/dart2js/simple_inferrer_final_field2_test.dart

Index: tests/compiler/dart2js/simple_inferrer_final_field2_test.dart
diff --git a/tests/compiler/dart2js/simple_inferrer_final_field2_test.dart b/tests/compiler/dart2js/simple_inferrer_final_field2_test.dart
index 6967d560e33d7f288ba680ca221acb389df61170..d81f3fc69563f4c8831c0194d424282c2948139c 100644
--- a/tests/compiler/dart2js/simple_inferrer_final_field2_test.dart
+++ b/tests/compiler/dart2js/simple_inferrer_final_field2_test.dart
@@ -31,7 +31,7 @@ void main() {
         var typesInferrer = compiler.globalInference.typesInferrerInternal;
 
         checkFieldTypeInClass(String className, String fieldName, type) {
-          var cls = findElement(compiler, className);
+          dynamic cls = findElement(compiler, className);
           var element = cls.lookupLocalMember(fieldName);
           Expect.isTrue(
               typesInferrer.getTypeOfElement(element).containsOnly(type));