RFR 8234423 : More accurate handling of modification counter in ArrayList.SubList.Iterator

[Ivan Gerasimov]

Hello!

When a sublist of a sublist of an ArrayList is created, its modCount is 
initialized from the ArrayList root, and not from its immediate parent.

This means that modifying that 2nd level sublist will reset modCounts of 
the entire chain up to the root, and consequently the 1st level sublist 
won't detect concurrent modification done to the ArrayList root.

Along with the fix, handling of modCount is slightly improved in a few 
other places.

Would you please help review the fix?

BUGURL: https://bugs.openjdk.java.net/browse/JDK-8234423
WEBREV: http://cr.openjdk.java.net/~igerasim/8234423/00/webrev/

-- 
With kind regards,
Ivan Gerasimov