[8u] RFR (S) 8251397: NPE on ClassValue.ClassValueMap.cacheArray

[Aleksey Shipilev]

Original bug:
   https://bugs.openjdk.java.net/browse/JDK-8251397
   https://git.openjdk.java.net/jdk/commit/81e2cf82

Original patch does not apply cleanly to 8u, because the context is different. I reapplied most 
(all, actually) hunks by hand.

8u variant:
   https://cr.openjdk.java.net/~shade/8251397/webrev.8u.01/

Testing: tier1

-- 
Thanks,
-Aleksey