Fix equality type problem.

pkg/collection_helpers/lib/equality.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.
 
 /**
  * Defines equality relations on collections.
  */
 library dart.collection_helper.equality;
 
 import "dart:collection";
@@ skipping 29 matching lines @@
    */
   bool isValidKey(Object o);
 }
 
 /**
  * Equality of objects that compares only the natural equality of the objects.
  *
  * This equality uses the objects' own [Object.==] and [Object.hashCode] for
  * the equality.
  */
-class DefaultEquality implements Equality<Object> {
+class DefaultEquality implements Equality {
   const DefaultEquality();
   bool equals(Object e1, Object e2) => e1 == e2;
   int hash(Object e) => e.hashCode;
   bool isValidKey(Object o) => true;
 }
 
 /**
  * Equality of objects that compares only the identity of the objects.
  */
-class IdentityEquality implements Equality<Object> {
+class IdentityEquality implements Equality {
   const IdentityEquality();
   bool equals(Object e1, Object e2) => identical(e1, e2);
   int hash(Object e) => identityHashCode(e);
   bool isValidKey(Object o) => true;
 }
 
 /**
  * Equality on iterables.
  *
  * Two iterables are equal if they have the same elements in the same order.
@@ skipping 339 matching lines @@
       if (o is List) return new ListEquality(this).hash(o);
       if (o is Iterable) return new IterableEquality(this).hash(o);
     } else if (o is Iterable) {
       return new UnorderedIterableEquality(this).hash(o);
     }
     return _base.hash(o);
   }
 
   bool isValidKey(Object o) => o is Iterable || o is Map || _base.isValidKey(o);
 }