Make int and double nullable by default

test/checker/checker_test.dart

Index: test/checker/checker_test.dart
diff --git a/test/checker/checker_test.dart b/test/checker/checker_test.dart
index 49a7c4315bdc300f671c98bbdf194d44a8dfd2bb..8beca3212ed8a8024ff99fdd906091cd0172784c 100644
--- a/test/checker/checker_test.dart
+++ b/test/checker/checker_test.dart
@@ -85,7 +85,7 @@ main() {
           b = true;
         }
       '''
-    });
+    }, nonnullableTypes: <String>['int', 'double']);
   });
 
   test('Primitives and generics', () {
@@ -127,7 +127,7 @@ main() {
           T foo() => /*warning:DownCastLiteral*/null;
         }
       '''
-    });
+    }, nonnullableTypes: <String>['int', 'double']);
   });
 
   test('Constructors', () {