Change cascade style for DefaultDirtyCheckEventListener to persist on flush

The default cascade for it was SaveUpdate (via base AbstractFlushingEventListener) which triggered
insertion of the entities with post-insert style ID generators (eg. identity). Persist on the other hand will
make sure that insertion of the entity is delyed until flush is called.

Fixes nhibernate#1413

Author: hazzik

src/NHibernate.Test/Async/NHSpecificTest/GH1413/FixtureByCode.cs

@@ -74,13 +74,12 @@ protected override void OnTearDown()
 			}
 		}
 
-		[Test]
-		[KnownBug("#1413")]
-		public async Task SessionIsDirtyShouldNotTriggerCascadeSavingAsync()
+		[Theory]
+		public async Task SessionIsDirtyShouldNotTriggerCascadeSavingAsync(bool beginTransaction)
 		{
 			Sfi.Statistics.IsStatisticsEnabled = true;
 			using (var session = OpenSession())
-			using (session.BeginTransaction())
+			using (beginTransaction ? session.BeginTransaction() : null)
 			{
 				var parent = await (GetParentAsync(session));
 				var entityChild = new EntityChild

src/NHibernate.Test/NHSpecificTest/GH1413/FixtureByCode.cs

@@ -62,13 +62,12 @@ protected override void OnTearDown()
 			}
 		}
 
-		[Test]
-		[KnownBug("#1413")]
-		public void SessionIsDirtyShouldNotTriggerCascadeSaving()
+		[Theory]
+		public void SessionIsDirtyShouldNotTriggerCascadeSaving(bool beginTransaction)
 		{
 			Sfi.Statistics.IsStatisticsEnabled = true;
 			using (var session = OpenSession())
-			using (session.BeginTransaction())
+			using (beginTransaction ? session.BeginTransaction() : null)
 			{
 				var parent = GetParent(session);
 				var entityChild = new EntityChild

src/NHibernate/Async/Event/Default/DefaultDirtyCheckEventListener.cs

@@ -9,6 +9,8 @@
 
 
 using System;
+using NHibernate.Engine;
+using NHibernate.Util;
 
 namespace NHibernate.Event.Default
 {

src/NHibernate/Event/Default/DefaultDirtyCheckEventListener.cs

@@ -1,4 +1,6 @@
 using System;
+using NHibernate.Engine;
+using NHibernate.Util;
 
 namespace NHibernate.Event.Default
 {
@@ -11,6 +13,10 @@ public partial class DefaultDirtyCheckEventListener : AbstractFlushingEventListe
 	{
 		private static readonly INHibernateLogger log = NHibernateLogger.For(typeof(DefaultDirtyCheckEventListener));
 
+		protected override object Anything => IdentityMap.Instantiate(10);
+
+		protected override CascadingAction CascadingAction => CascadingAction.Persist;
+
 		public virtual void OnDirtyCheck(DirtyCheckEvent @event)
 		{
 			int oldSize = @event.Session.ActionQueue.CollectionRemovalsCount;