Fixing analyzer error in polymer_expressions.

pkg/polymer_expressions/lib/expression.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.
 
 library polymer_expressions.expression;
 
 import 'visitor.dart';
 
 // Helper functions for building expression trees programmatically
 
@@ skipping 205 matching lines @@
   if (a == null || b == null) return false;
   if (a.length != b.length) return false;
   for (int i = 0; i < a.length; i++) {
     if (a[i] != b[i]) return false;
   }
   return true;
 }
 
 int _hashList(List l) {
   var hash = l.fold(0,
-      (hash, item) => _JenkinsSmiHash.combine(hash, item.hashCode));
+      (h, item) => _JenkinsSmiHash.combine(h, item.hashCode));
   return _JenkinsSmiHash.finish(hash);
 }
 
 class _JenkinsSmiHash {
   // TODO: Bug 11617- This class should be optimized and standardized elsewhere.
 
   static int combine(int hash, int value) {
     hash = 0x1fffffff & (hash + value);
     hash = 0x1fffffff & (hash + ((0x0007ffff & hash) << 10));
     return hash ^ (hash >> 6);
   }
 
   static int finish(int hash) {
     hash = 0x1fffffff & (hash + ((0x03ffffff & hash) <<  3));
     hash = hash ^ (hash >> 11);
     return 0x1fffffff & (hash + ((0x00003fff & hash) << 15));
   }
 
   static int hash2(a, b) => finish(combine(combine(0, a), b));
 
   static int hash3(a, b, c) => finish(combine(combine(combine(0, a), b), c));
 
   static int hash4(a, b, c, d) =>
       finish(combine(combine(combine(combine(0, a), b), c), d));
 }