[8u] RFR 8075939: Stream.flatMap() causes breaking of short-circuiting of terminal operations

[Aleksey Shipilev]

This is a frequent complaint about 8u streams support:
  https://bugs.openjdk.java.net/browse/JDK-8075939

Original fix:
  http://hg.openjdk.java.net/jdk/jdk10/rev/fca88bbbafb9

Patch does not apply cleanly to 8u even after reshuffling: it uses "var" at some places.

8u webrev:
  http://cr.openjdk.java.net/~shade/8075939/webrev.8u.01/

Testing: java/util tests, includes new test cases

-- 
Thanks,
-Aleksey