Use closure conversion in new dart2js backend.

pkg/compiler/lib/src/cps_ir/shrinking_reductions.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.
 
 part of dart2js.cps_ir.optimizers;
 
 /**
  * [ShrinkingReducer] applies shrinking reductions to CPS terms as described
  * in 'Compiling with Continuations, Continued' by Andrew Kennedy.
  */
@@ skipping 402 matching lines @@
   // JavaScript specific nodes.
 
   processIdentical(Identical node) {
     node.left.parent = node;
     node.right.parent = node;
   }
 
   processInterceptor(Interceptor node) {
     node.input.parent = node;
   }
+
+  processSetField(SetField node) {
+    node.object.parent = node;
+    node.value.parent = node;
+    node.body.parent = node;
+  }
+
+  processGetField(GetField node) {
+    node.object.parent = node;
+  }
+
+  processCreateClosureClass(CreateClosureClass node) {
+    node.arguments.forEach((Reference ref) => ref.parent = node);
+  }
+
+  processCreateBox(CreateBox node) {
+  }
 }
 
 class _ReductionKind {
   final String name;
   final int hashCode;
 
   const _ReductionKind(this.name, this.hashCode);
 
   static const _ReductionKind DEAD_VAL = const _ReductionKind('dead-val', 0);
   static const _ReductionKind DEAD_CONT = const _ReductionKind('dead-cont', 1);
@@ skipping 26 matching lines @@
   }
 
   String toString() => "$kind: $node";
 }
 
 /// A dummy class used solely to mark nodes as deleted once they are removed
 /// from a term.
 class _DeletedNode extends Node {
   accept(_) => null;
 }