refactoring

svn path=/trunk/mcs/; revision=102828

mcs/class/System.Core/System.Linq/Enumerable.cs

@@ -1687,10 +1687,10 @@ namespace System.Linq
 			Check.Source (source);
 
 			IList<TSource> list = source as IList<TSource>;
-			if (list != null)
-				return CreateReverseIterator (list);
+			if (list == null)
+				list = new List<TSource> (source);
 
-			return CreateReverseIterator (source);
+			return CreateReverseIterator (list);
 		}
 
 		static IEnumerable<TSource> CreateReverseIterator<TSource> (IList<TSource> source)
@@ -1699,13 +1699,6 @@ namespace System.Linq
 				yield return source [i - 1];
 		}
 
-		static IEnumerable<TSource> CreateReverseIterator<TSource> (IEnumerable<TSource> source)
-		{
-			var list = new List<TSource> (source);
-			list.Reverse ();
-			return list;
-		}
-
 		#endregion
 
 		#region Select