Split js_backend_cps_ir tests into multiple test units.

tests/compiler/dart2js/js_backend_cps_ir_closures_test.dart

Index: tests/compiler/dart2js/js_backend_cps_ir_closures_test.dart
diff --git a/tests/compiler/dart2js/js_backend_cps_ir_closures.dart b/tests/compiler/dart2js/js_backend_cps_ir_closures_test.dart
similarity index 94%
rename from tests/compiler/dart2js/js_backend_cps_ir_closures.dart
rename to tests/compiler/dart2js/js_backend_cps_ir_closures_test.dart
index 2e18e304acc63b061dd0f636a8fc74d921e937df..125bf2b7c0ff7f8199108ef319b8e0dd1bc1c88d 100644
--- a/tests/compiler/dart2js/js_backend_cps_ir_closures.dart
+++ b/tests/compiler/dart2js/js_backend_cps_ir_closures_test.dart
@@ -1,12 +1,13 @@
 // 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
 
-// Tests of interceptors.
+// Tests of closures.
 
 library closures_test;
 
-import 'js_backend_cps_ir_test.dart';
+import 'js_backend_cps_ir.dart';
 
 const List<TestEntry> tests = const [
   const TestEntry("""
@@ -123,3 +124,7 @@ function() {
   }
 }"""),
 ];
+
+void main() {
+  runTests(tests);
+}