Set up a stub pipline for using the new cps-based ir to generate js.

tests/compiler/dart2js/backend_dart/dart_new_backend_test.dart

Index: tests/compiler/dart2js/backend_dart/dart_new_backend_test.dart
diff --git a/tests/compiler/dart2js/backend_dart/dart_new_backend_test.dart b/tests/compiler/dart2js/backend_dart/dart_new_backend_test.dart
index 0861957b8f232249106d13fcaf4c025f70a4c6f0..d1f4e5c1e0e0e2d568654179341311c37456cc37 100644
--- a/tests/compiler/dart2js/backend_dart/dart_new_backend_test.dart
+++ b/tests/compiler/dart2js/backend_dart/dart_new_backend_test.dart
@@ -34,7 +34,7 @@ Future<String> compile(String code) {
     compiler.processQueue(compiler.enqueuer.resolution, element);
     compiler.world.populate();
     compiler.backend.onResolutionComplete();
-    compiler.irBuilder.buildNodes(useNewBackend: true);
+    compiler.irBuilder.buildNodes();
     compiler.phase = Compiler.PHASE_COMPILING;
     DartBackend backend = compiler.backend;
     backend.assembleProgram();