A typed selector needs no such method handling if at least one of its implemented subtype (in case …

tests/language/no_such_method_subtype_test.dart

Index: tests/language/no_such_method_subtype_test.dart
===================================================================
--- tests/language/no_such_method_subtype_test.dart	(revision 0)
+++ tests/language/no_such_method_subtype_test.dart	(revision 0)
@@ -0,0 +1,27 @@
+// Copyright (c) 2013, 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 "package:expect/expect.dart";
+
+class A {
+  foo() => 42;
+}
+
+class B implements A {
+  noSuchMethod(im) => 84;
+}
+
+main() {
+  var a = [new A(), new B()];
+  var b = a[1];
+  if (b is A) {
+    // `b.foo()` will create a typed selector whose receiver type is a
+    // subtype of `A`. Because not all subtypes of `A` implement
+    // `foo`, dart2js must generate a `noSuchMethod` stub for `foo` in
+    // the top Object class.
+    Expect.equals(84, b.foo());
+    return;
+  }
+  Expect.fail('Should not be here');
+}