Use closure conversion in new dart2js backend.

tests/compiler/dart2js/js_backend_cps_ir_test.dart

 // 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.
 // VMOptions=-DUSE_CPS_IR=true
 
 // Test that the CPS IR code generator compiles programs and produces the
 // the expected output.
 
 import 'package:async_helper/async_helper.dart';
 import 'package:expect/expect.dart';
 import 'package:compiler/src/apiimpl.dart'
        show Compiler;
 import 'memory_compiler.dart';
 import 'package:compiler/src/js/js.dart' as js;
 import 'package:compiler/src/common.dart' show Element;
 
 import 'js_backend_cps_ir_basic.dart' as basic;
 import 'js_backend_cps_ir_literals.dart' as literals;
 import 'js_backend_cps_ir_operators.dart' as operators;
 import 'js_backend_cps_ir_control_flow.dart' as control_flow;
 import 'js_backend_cps_ir_interceptors.dart' as interceptors;
+import 'js_backend_cps_ir_closures.dart' as closures;
 
 const String TEST_MAIN_FILE = 'test.dart';
 
 List<TestEntry> tests = <TestEntry>[]
      ..addAll(basic.tests)
      ..addAll(literals.tests)
      ..addAll(control_flow.tests)
      ..addAll(operators.tests)
-     ..addAll(interceptors.tests);
+     ..addAll(interceptors.tests)
+     ..addAll(closures.tests);
 
 class TestEntry {
   final String source;
   final String expectation;
   const TestEntry(this.source, [this.expectation]);
 }
 
 String formatTest(Map test) {
   return test[TEST_MAIN_FILE];
 }
@@ skipping 23 matching lines @@
           }
         }
       }).catchError((e) {
         print(e);
         Expect.fail('The following test failed to compile:\n'
                     '${formatTest(files)}');
       });
     });
   }
 }