Correctly pass constructor arguments to _HMAC.

sdk/lib/crypto/crypto.dart

 // Copyright (c) 2012, 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('dart:crypto');
 
 #import('dart:math');
 
 #source('crypto_utils.dart');
 #source('hash_utils.dart');
@@ skipping 65 matching lines @@
 /**
  * Hash-based Message Authentication Code support.
  *
  * The [update] method is used to add data to the message. The [digest] method
  * is used to extract the message authentication code.
  */
 abstract class HMAC {
   /**
    * Create an [HMAC] object from a [Hash] and a key.
    */
-  factory HMAC(Hash hash, List<int> key) => new _HMAC();
+  factory HMAC(Hash hash, List<int> key) => new _HMAC(hash, key);
 
   /**
    * Add a list of bytes to the message.
    */
   HMAC update(List<int> data);
 
   /**
    * Perform the actual computation and extract the message digest
    * as a list of bytes.
    */
@@ skipping 25 matching lines @@
 /**
  * HashExceptions are thrown on invalid use of a Hash
  * object.
  */
 class HashException {
   HashException(String this.message);
   toString() => "HashException: $message";
   String message;
 }