dart2js: is-checks for the new emitter.

tests/language/generic_instanceof5_test.dart

Index: tests/language/generic_instanceof5_test.dart
diff --git a/tests/language/generic_instanceof5_test.dart b/tests/language/generic_instanceof5_test.dart
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index 0000000000000000000000000000000000000000..97fc11a52baafa777e0fe86ca96df5d7527430b9
--- /dev/null
+++ b/tests/language/generic_instanceof5_test.dart
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+// 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.
+// Test that instanceof works correctly with type variables.
+
+import "package:expect/expect.dart";
+
+class A {
+}
+
+class B<T, S> {
+}
+
+class C<U, V> extends A with B<V, U> {}
+
+class D<T> {
+  foo(x) {
+    // Avoid inlining.
+    if (new DateTime.now().millisecondsSinceEpoch == 42) foo(x);
+    return x is T;
+    return true;  // Avoid inlining.
+  }
+}
+
+main() {
+  Expect.isTrue(new D<B<int, bool>>().foo(new C<bool, int>()));
+}