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

pkg/compiler/lib/src/compiler.dart

 // Copyright (c) 2012, 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.
 
 part of dart2js;
 
 /**
  * If true, print a warning for each method that was resolved, but not
  * compiled.
  */
@@ skipping 1471 matching lines @@
     assert(mainFunction != null);
     phase = PHASE_DONE_RESOLVING;
 
     world.populate();
     // Compute whole-program-knowledge that the backend needs. (This might
     // require the information computed in [world.populate].)
     backend.onResolutionComplete();
 
     deferredLoadTask.onResolutionComplete(mainFunction);
 
     log('Building IR...');

[floitsch, 2014/11/13 14:30:55]

move log into if.

[sigurdm, 2014/11/13 14:43:41]

Done.

-    irBuilder.buildNodes();
+    if (const bool.fromEnvironment('USE_NEW_BACKEND')) {
+      irBuilder.buildNodes();
+    }
 
     log('Inferring types...');
     typesTask.onResolutionComplete(mainFunction);
 
     if (stopAfterTypeInference) return;
 
     log('Compiling...');
     phase = PHASE_COMPILING;
     // TODO(johnniwinther): Move these to [CodegenEnqueuer].
     if (hasIsolateSupport) {
@@ skipping 671 matching lines @@
   int warnings = 0;
   int hints = 0;
 }
 
 class GenericTask extends CompilerTask {
   final String name;
 
   GenericTask(this.name, Compiler compiler)
       : super(compiler);
 }