Add some tests.

tests/language/src/Operator4Test.dart

Index: tests/language/src/Operator4Test.dart
diff --git a/tests/language/src/Operator4Test.dart b/tests/language/src/Operator4Test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..642fef90673a5bf33308cee7ba30adc73a65c975
--- /dev/null
+++ b/tests/language/src/Operator4Test.dart
@@ -0,0 +1,21 @@
+// Copyright (c) 2011, 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 A {
+  operator <(other) => 1;
+}
+
+// This triggered a bug in Dart2Js: relational operators were not correctly
+// boolified.
+foo(a) {
+  if (a < a) {
+    return "bad";
+  } else {
+    return 499;
+  }
+}
+
+main() {
+  Expect.equals(499, foo(new A()));
+}