Add test of unittests.

tests/compiler/dart2js/js_backend_cps_ir_codeUnitAt_test.dart

 // Copyright (c) 2015, 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.
 
 // Tests for constant folding and lowering String.codeUnitAt.
 
-library basic_tests;
+library codeUnitAt_tests;
 
 import 'js_backend_cps_ir.dart';
 
 const List<TestEntry> tests = const [
 
   // Constant folding.
   const TestEntry(r"""
 main() {
   print('A'.codeUnitAt(0));
 }""",r"""
@@ skipping 28 matching lines @@
   for (; i < v0; sum = sum + s.charCodeAt(i), i = i + 1)
     ;
   return sum;
 }"""),
 ];
 
 
 void main() {
   runTests(tests);
 }