Correctly pass constructor arguments to _HMAC.

sdk/lib/crypto/crypto.dart

Index: sdk/lib/crypto/crypto.dart
diff --git a/sdk/lib/crypto/crypto.dart b/sdk/lib/crypto/crypto.dart
index c8f9a0f5a9e724e5ce7ce4e37fc24b31cd9306ae..1064ca01a40e0686d092aa7d146fae629dc0fb0a 100644
--- a/sdk/lib/crypto/crypto.dart
+++ b/sdk/lib/crypto/crypto.dart
@@ -83,7 +83,7 @@ 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.