Strong mode cleaning of many dart2js tests.

tests/compiler/dart2js/simple_inferrer_final_field_test.dart

Index: tests/compiler/dart2js/simple_inferrer_final_field_test.dart
diff --git a/tests/compiler/dart2js/simple_inferrer_final_field_test.dart b/tests/compiler/dart2js/simple_inferrer_final_field_test.dart
index 7b140572a5d19db958bc05fff95a15b4eba31e3e..9f2ca0e5d225f103453f56a2d9b05b1ff7a5c0fb 100644
--- a/tests/compiler/dart2js/simple_inferrer_final_field_test.dart
+++ b/tests/compiler/dart2js/simple_inferrer_final_field_test.dart
@@ -35,7 +35,7 @@ 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));