[dart2wasm] Add dynamic modules subtyping test.

Tests that types defined fully with dynamic modules type check correctly.

In WASM this ensures that the class ID ranges used for the type checks are correct.

Change-Id: I22aa528599eb918062e198b878ba2b4cdc901a06
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/430620
Auto-Submit: Nate Biggs <[email protected]>
Reviewed-by: Martin Kustermann <[email protected]>
Commit-Queue: Nate Biggs <[email protected]>

Author: natebiggs

pkg/dynamic_modules/test/data/submodule_type_check/dynamic_interface.yaml

@@ -0,0 +1,3 @@
+# Copyright (c) 2025, 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.

pkg/dynamic_modules/test/data/submodule_type_check/main.dart

@@ -0,0 +1,11 @@
+// Copyright (c) 2025, 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.
+
+import '../../common/testing.dart' as helper;
+
+void main() async {
+  await helper.load('entry1.dart');
+  await helper.load('entry2.dart');
+  helper.done();
+}

pkg/dynamic_modules/test/data/submodule_type_check/modules/entry1.dart

@@ -0,0 +1,12 @@
+// Copyright (c) 2025, 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.
+
+class Child {}
+
+Object getChild(int x) {
+  return x < 3 ? Child() : 4;
+}
+
+@pragma('dyn-module:entry-point')
+Object? dynamicModuleEntrypoint() => getChild(1) as Child;

pkg/dynamic_modules/test/data/submodule_type_check/modules/entry2.dart

@@ -0,0 +1,12 @@
+// Copyright (c) 2025, 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.
+
+class Child {}
+
+Object getChild(int x) {
+  return x < 3 ? Child() : 4;
+}
+
+@pragma('dyn-module:entry-point')
+Object? dynamicModuleEntrypoint() => getChild(1) as Child;