Use "Object" as the reified type of covariant override parameters.

pkg/dev_compiler/test/not_yet_strong_tests.dart

Index: pkg/dev_compiler/test/not_yet_strong_tests.dart
diff --git a/pkg/dev_compiler/test/not_yet_strong_tests.dart b/pkg/dev_compiler/test/not_yet_strong_tests.dart
index 2544ae8abf73489a4103c9db274e58b0a4cd42e6..7cf87ccf876e6eb46fdcbad0d4e90afda7cb1275 100644
--- a/pkg/dev_compiler/test/not_yet_strong_tests.dart
+++ b/pkg/dev_compiler/test/not_yet_strong_tests.dart
@@ -517,7 +517,6 @@ final notYetStrongTests = new HashSet<String>.from([
   'language/cyclic_class_member_test_01_multi',
   'language/cyclic_constructor_test_01_multi',
   'language/cyclic_default_values_test',
-  'language/cyclic_import_test',
   'language/cyclic_type_variable_test_01_multi',
   'language/cyclic_type_variable_test_02_multi',
   'language/cyclic_type_variable_test_03_multi',
@@ -2396,6 +2395,11 @@ final notYetStrongTests = new HashSet<String>.from([
   'lib/convert/chunked_conversion_utf8_test',
   'lib/convert/line_splitter_test',
   'lib/html/cross_frame_test',
+  'lib/html/custom/constructor_calls_created_synchronously_test',
+  'lib/html/custom/created_callback_test',
+  'lib/html/custom/document_register_basic_test',
+  'lib/html/custom/document_register_type_extensions_test',
+  'lib/html/custom/element_upgrade_test',
   'lib/html/element_test',
   'lib/html/events_test',
   'lib/html/fileapi_test',