Use assertSubtype for lists.

tests/language/generic_list_checked_test.dart

Index: tests/language/generic_list_checked_test.dart
diff --git a/tests/language/interceptor7_test.dart b/tests/language/generic_list_checked_test.dart
similarity index 57%
copy from tests/language/interceptor7_test.dart
copy to tests/language/generic_list_checked_test.dart
index 965ddfc800c1b1fa7971bd918391b1e806c00cf3..fcff24bc2e8e906492bf4e10e4825d337d199018 100644
--- a/tests/language/interceptor7_test.dart
+++ b/tests/language/generic_list_checked_test.dart
@@ -2,15 +2,19 @@
 // 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.
 
-// Test that dart2js uses the right interceptor when call a method on
-// something that has type number.
-
 import 'package:expect/expect.dart';
 
-var array = [];
+bool inCheckedMode() {
+  try {
+    int i = 'hest';
+  } catch (e) {
+    return true;
+  }
+  return false;
+}
 
 main() {
-  array.add(false);
-  var x = array[0] ? 1.5 : 2;
-  Expect.isTrue(x.isEven);
+  if (inCheckedMode()) {
+    Expect.throws(() { List<int> t = new List<String>(); });
+  }
 }