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

pkg/compiler/lib/src/dart_backend/logical_rewriter.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.
 
 library logical_rewriter;
 
 import '../constants/values.dart' as values;
-import 'tree_ir_nodes.dart';
+import '../tree_ir/tree_ir_nodes.dart';
 
 /// Rewrites logical expressions to be more compact in the Tree IR.
 ///
 /// In this class an expression is said to occur in "boolean context" if
 /// its result is immediately applied to boolean conversion.
 ///
 /// IF STATEMENTS:
 ///
 /// We apply the following two rules to [If] statements (see [visitIf]).
 ///
@@ skipping 425 matching lines @@
   }
 
   /// Destructively updates each entry of [l] with the result of visiting it.
   void _rewriteList(List<Expression> l) {
     for (int i = 0; i < l.length; i++) {
       l[i] = visitExpression(l[i]);
     }
   }
 }