Request for reviews (S): 6916062: assert(_inserts <= _insert_limit, "hash table overflow") in NodeHash::hash_insert

[Vladimir Kozlov]

http://cr.openjdk.java.net/~kvn/6916062/webrev.02

Fixed 6916062: assert(_inserts <= _insert_limit,"hash table overflow") in NodeHash::hash_insert

Changes for 6711117 put a memory node back on IGVN
worklist if address type does not match cached type
in a hope that address nodes will be processed and
the type will be updated. But it does not check that
there are nodes on worklist which will trigger address
processing. As result the memory node is pulled from
and pushed on IGVN worklist infinitely.
On each iteration NodeHash::_inserts value is incremented
forcing hash table grow until integer value NodeHash::_max
is overflow (became 0) which triggers bug's assert.

I decided to go with simplest fix which is easy to backport
and leave fixing address type inconsistency for later
(I have bug 6715629).
I also added asserts to catch such situations.

Tested with failing case, CTW, JPRT.