Fix 8586 8587 - [Tizen] Added guard for CollectionView (#9367) fixes #8586 #8587

* [Tizen] Remove events on unbinding in CollectionView

- Resolves bug #8587

* [Tizen] Guard for sizeless layout requests in CollectionView

- Resolves bug #8586

Xamarin.Forms.Platform.Tizen/Native/CollectionView/CollectionView.cs

@@ -495,6 +495,9 @@ namespace Xamarin.Forms.Platform.Tizen.Native
 
 		void RequestLayoutItems()
 		{
+			if (AllocatedSize.Width <= 0 || AllocatedSize.Height <= 0)
+				return;
+
 			if (!_requestLayoutItems)
 			{
 				_requestLayoutItems = true;

Xamarin.Forms.Platform.Tizen/Native/CollectionView/GridLayoutManager.cs

@@ -115,6 +115,9 @@ namespace Xamarin.Forms.Platform.Tizen.Native
 
 		public void LayoutItems(Rect bound, bool force)
 		{
+			if (_allocatedSize.Width <= 0 || _allocatedSize.Height <= 0)
+				return;
+
 			// TODO : need to optimization. it was frequently called with similar bound value.
 			if (!ShouldRearrange(bound) && !force)
 			{

Xamarin.Forms.Platform.Tizen/Native/CollectionView/ItemTemplateAdaptor.cs

@@ -104,9 +104,9 @@ namespace Xamarin.Forms.Platform.Tizen.Native
 
 		public override void RemoveNativeView(EvasObject native)
 		{
+			UnBinding(native);
 			if (_nativeFormsTable.TryGetValue(native, out View view))
 			{
-				ResetBindedView(view);
 				Platform.GetRenderer(view)?.Dispose();
 				_nativeFormsTable.Remove(native);
 			}
@@ -178,7 +178,7 @@ namespace Xamarin.Forms.Platform.Tizen.Native
 			int index = GetItemIndex(data);
 			if (index != -1)
 			{
-				CollectionView.ItemMeasureInvalidated(index);
+				CollectionView?.ItemMeasureInvalidated(index);
 			}
 		}
 	}

Xamarin.Forms.Platform.Tizen/Native/CollectionView/LinearLayoutManager.cs

@@ -110,6 +110,9 @@ namespace Xamarin.Forms.Platform.Tizen.Native
 
 		public void LayoutItems(Rect bound, bool force)
 		{
+			if (_allocatedSize.Width <= 0 || _allocatedSize.Height <= 0)
+				return;
+
 			// TODO : need to optimization. it was frequently called with similar bound value.
 			if (!ShouldRearrange(bound) && !force)
 			{