RFR [9] 8011645: CopyOnWriteArrayList.COWSubList.subList does not validate range properly

[Chris Hegarty]

Trivial change to CopyOnWriteArrayList.COWSubList.subList to catch the 
case where the fromIndex is greater that the toIndex.

http://cr.openjdk.java.net/~chegar/8011645/webrev.00/webrev/
-Chris.