fix ListView index on click when ListView has no header

Author: heikow10

Xamarin.Forms.Platform.Android/CellAdapter.cs

@@ -132,13 +132,12 @@ bool AActionMode.ICallback.OnPrepareActionMode(AActionMode mode, IMenu menu)
 
 		public void OnItemClick(AdapterView parent, AView view, int position, long id)
 		{
+			var listView = parent as AListView;
+			if (listView != null)
+				position -= listView.HeaderViewsCount;
+
 			if (_actionMode != null || _supportActionMode != null)
-			{
-				var listView = parent as AListView;
-				if (listView != null)
-					position -= listView.HeaderViewsCount;
 				HandleContextMode(view, position);
-			}
 			else
 				HandleItemClick(parent, view, position, id);
 		}

Xamarin.Forms.Platform.Android/Renderers/ListViewAdapter.cs

@@ -481,9 +481,6 @@ protected override void HandleItemClick(AdapterView parent, AView view, int posi
 				cell = (Cell)(cellOwner as INativeElementView)?.Element;
 			}
 
-			// All our ListView's have called AddHeaderView. This effectively becomes index 0, so our index 0 is index 1 to the listView.
-			position--;
-
 			if (position < 0 || position >= Count)
 				return;