Use closure conversion in new dart2js backend.

pkg/compiler/lib/src/tree_ir/optimization/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.
 
 part of tree_ir.optimization;
 
 /// 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.
@@ skipping 297 matching lines @@
 
     return node;
   }
 
   Expression visitLogicalOperator(LogicalOperator node) {
     node.left = makeCondition(node.left, true);
     node.right = makeCondition(node.right, true);
     return node;
   }
 
+  Statement visitSetField(SetField node) {
+    node.object = visitExpression(node.object);
+    node.value = visitExpression(node.value);
+    node.next = visitStatement(node.next);
+    return node;
+  }
+
+  Expression visitGetField(GetField node) {
+    node.object = visitExpression(node.object);
+    return node;
+  }
+
+  Expression visitCreateBox(CreateBox node) {
+    return node;
+  }
+
+  Expression visitCreateClosureClass(CreateClosureClass node) {
+    _rewriteList(node.arguments);
+    return node;
+  }
+
   /// True if the given expression is known to evaluate to a boolean.
   /// This will not recursively traverse [Conditional] expressions, but if
   /// applied to the result of [visitExpression] conditionals will have been
   /// rewritten anyway.
   bool isBooleanValued(Expression e) {
     return isTrue(e) || isFalse(e) || e is Not || e is LogicalOperator;
   }
 
   /// Rewrite an expression that was originally processed in a non-boolean
   /// context.
@@ skipping 133 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]);
     }
   }
 }