Do not ignore side effects of a type test or type cast as expression, such

tests/language/malbounded_type_test2_test.dart

Index: tests/language/malbounded_type_test2_test.dart
===================================================================
--- tests/language/malbounded_type_test2_test.dart	(revision 0)
+++ tests/language/malbounded_type_test2_test.dart	(revision 0)
@@ -0,0 +1,32 @@
+// Copyright (c) 2014, 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";
+
+isCheckedMode() {
+  try {
+    var i = 1;
+    String s = i;
+    return false;
+  } catch (e) {
+    return true;
+  }
+}
+
+class A<T extends num> { }
+
+class B<T> {
+  test() {
+    new A() is A<T>;  /// static type warning
+  }
+}
+
+main () {
+  var b = new B<String>();
+  if (isCheckedMode()) {
+    Expect.throws(() => b.test(), (e) => e is TypeError);
+  } else {
+    b.test();
+  }
+}