Strong mode cleaning of many dart2js tests.

tests/compiler/dart2js/simple_inferrer_final_field3_test.dart

Index: tests/compiler/dart2js/simple_inferrer_final_field3_test.dart
diff --git a/tests/compiler/dart2js/simple_inferrer_final_field3_test.dart b/tests/compiler/dart2js/simple_inferrer_final_field3_test.dart
index c321c54ca2f0f0bd09ecf83064cb990e4c6f142f..9c530bd0a4c516a6a712c8729fdc5d8d99638dc6 100644
--- a/tests/compiler/dart2js/simple_inferrer_final_field3_test.dart
+++ b/tests/compiler/dart2js/simple_inferrer_final_field3_test.dart
@@ -31,7 +31,7 @@ void main() {
         var closedWorld = typesInferrer.closedWorld;
 
         checkFieldTypeInClass(String className, String fieldName, type) {
-          var cls = findElement(compiler, className);
+          dynamic cls = findElement(compiler, className);
           var element = cls.lookupLocalMember(fieldName);
           Expect.equals(type,
               simplify(typesInferrer.getTypeOfElement(element), closedWorld));