[ffigen] Move property tests into "native_objc_test" group

pkgs/ffigen/test/native_objc_test/native_objc_test.dart

diff --git a/pkgs/ffigen/test/native_objc_test/native_objc_test.dart b/pkgs/ffigen/test/native_objc_test/native_objc_test.dart
index f32b0b7..a4f2a57 100644
--- a/pkgs/ffigen/test/native_objc_test/native_objc_test.dart
+++ b/pkgs/ffigen/test/native_objc_test/native_objc_test.dart
@@ -80,18 +80,18 @@
       expect(str3.length, 11);
       expect(str3.toString(), "HelloWorld!");
     });
-  });
 
-  test('Instance read-only property', () {
-    expect(Foo.makeFoo(lib, 42).readOnlyProperty, 7);
-  });
+    test('Instance read-only property', () {
+      expect(Foo.makeFoo(lib, 42).readOnlyProperty, 7);
+    });
 
-  test('Class read-only property', () {
-    expect(Foo.getClassReadOnlyProperty(lib), 42);
-  });
+    test('Class read-only property', () {
+      expect(Foo.getClassReadOnlyProperty(lib), 42);
+    });
 
-  test('Class read-write property', () {
-    Foo.setClassReadWriteProperty(lib, 101);
-    expect(Foo.getClassReadWriteProperty(lib), 101);
+    test('Class read-write property', () {
+      Foo.setClassReadWriteProperty(lib, 101);
+      expect(Foo.getClassReadWriteProperty(lib), 101);
+    });
   });
 }