Remove the hashCode function from CPS nodes.

pkg/compiler/lib/src/cps_ir/cps_ir_nodes.dart

 // Copyright (c) 2013, 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.
 
 // IrNodes are kept in a separate library to have precise control over their
 // dependencies on other parts of the system.
 library dart2js.ir_nodes;
 
 import '../constants/expressions.dart';
 import '../constants/values.dart' as values show ConstantValue;
 import '../dart2jslib.dart' as dart2js show invariant;
 import '../elements/elements.dart';
 import '../universe/universe.dart' show Selector, SelectorKind;
 import '../dart_types.dart' show DartType, GenericType;
 
 abstract class Node {
-  static int hashCount = 0;
-  final int hashCode = hashCount = (hashCount + 1) & 0x3fffffff;
-
   /// A pointer to the parent node. Is null until set by optimization passes.
   Node parent;
 
   accept(Visitor visitor);
 }
 
 abstract class Expression extends Node {
   Expression plug(Expression expr) => throw 'impossible';
 }
 
@@ skipping 945 matching lines @@
   }
 
   // JavaScript specific nodes.
 
   void visitIdentical(Identical node) {
     visitReference(node.left);
     visitReference(node.right);
   }
 }