8003263: redundant cast build failure after 8003120

Reviewed-by: alanb

src/share/classes/com/sun/naming/internal/ResourceManager.java

@@ -560,8 +560,7 @@ public final class ResourceManager {
                     }
                 } finally {
                     while (resources.hasMore()) {
-                        InputStream istream = (InputStream)resources.next();
-                        istream.close();
+                        resources.next().close();
                     }
                 }