Make int and double nullable by default

test/checker/checker_test.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /// General type checking tests
 library ddc.test.checker_test;
 
 import 'package:unittest/compact_vm_config.dart';
 import 'package:unittest/unittest.dart';
 
@@ skipping 67 matching lines @@
           // num is nullable
           z = null;
           z = x;
           z = y;
 
           // bool is nullable
           b = null;
           b = true;
         }
       '''
-    });
+    }, nonnullableTypes: <String>['int', 'double']);
   });
 
   test('Primitives and generics', () {
     testChecker({
       '/main.dart': '''
         class A<T> {
           // TODO(vsm): This needs a static info indicating a runtime
           // check at construction.
           T x;
 
@@ skipping 21 matching lines @@
 
         class C<T extends num> {
           // TODO(vsm): This needs a static info indicating a runtime
           // check at construction.
           T x;
 
           // TODO(vsm): Should this be a different type of DownCast?
           T foo() => /*warning:DownCastLiteral*/null;
         }
       '''
-    });
+    }, nonnullableTypes: <String>['int', 'double']);
   });
 
   test('Constructors', () {
     testChecker({
       '/main.dart': '''
       const num z = 25;
       Object obj = "world";
 
       class A {
         int x;
@@ skipping 2563 matching lines @@
         '/main.dart': '''
             class A {}
             class T1 implements A {
                 /*severe:InferableOverride*/toString() {}
             }
          '''
       }, inferFromOverrides: false);
     });
   });
 }