Eliminate redundant code in Range.

Ix.NET/Source/System.Linq.Async/System/Linq/Operators/Range.cs

@@ -17,7 +17,7 @@ namespace System.Linq
                 throw Error.ArgumentOutOfRange(nameof(count));
 
             var end = (long)start + count - 1L;
-            if (count < 0 || end > int.MaxValue)
+            if (end > int.MaxValue)
                 throw Error.ArgumentOutOfRange(nameof(count));
 
             if (count == 0)