Fix equality type problem.

pkg/collection_helpers/lib/equality.dart

Index: pkg/collection_helpers/lib/equality.dart
diff --git a/pkg/collection_helpers/lib/equality.dart b/pkg/collection_helpers/lib/equality.dart
index e48d130de16210d1e122603562e7fbcbe12dc3a0..c52d30f8c5307320938edf30a3125d50e799cb9a 100644
--- a/pkg/collection_helpers/lib/equality.dart
+++ b/pkg/collection_helpers/lib/equality.dart
@@ -47,7 +47,7 @@ abstract class Equality<E> {
  * 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;
@@ -57,7 +57,7 @@ class DefaultEquality implements Equality<Object> {
 /**
  * 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);