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

pkg/compiler/lib/src/dart_backend/statement_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 statement_rewriter;
 
-import 'tree_ir_nodes.dart';
+import '../tree_ir/tree_ir_nodes.dart';
 
 /**
  * Performs the following transformations on the tree:
  * - Assignment propagation
  * - If-to-conditional conversion
  * - Flatten nested ifs
  * - Break inlining
  * - Redirect breaks
  *
  * The above transformations all eliminate statements from the tree, and may
@@ skipping 526 matching lines @@
   }
 
   Expression makeCondition(Expression e, bool polarity) {
     return polarity ? e : new Not(e);
   }
 
   Statement getBranch(If node, bool polarity) {
     return polarity ? node.thenStatement : node.elseStatement;
   }
 }