7194370: (fs) WatchService fails if volume S/N is 0 [win]

Reviewed-by: alanb, forax

src/windows/classes/sun/nio/fs/WindowsFileAttributes.java

 /*
- * Copyright (c) 2008, 2009, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2012, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -383,20 +383,14 @@ class WindowsFileAttributes
     }
 
     int volSerialNumber() {
-        if (volSerialNumber == 0)
-            throw new AssertionError("Should not get here");
         return volSerialNumber;
     }
 
     int fileIndexHigh() {
-        if (volSerialNumber == 0)
-            throw new AssertionError("Should not get here");
         return fileIndexHigh;
     }
 
     int fileIndexLow() {
-        if (volSerialNumber == 0)
-            throw new AssertionError("Should not get here");
         return fileIndexLow;
     }