RFR[8238286]: 'Add new flatMap stream operation that is more amenable to pushing’

[Florian Weimer]

* Patrick Concannon:

> webrev: http://cr.openjdk.java.net/~pconcannon/8238286/webrevs/webrev.05/

+     * <p>The results of this method are undefined if the second {@link IntConsumer}
+     * argument is operated on outside the scope of the mapper function.

Should this say “after the mapper function has returned”?  Otherwise,
one could argue that is possible to use a consumer from a previous
invocation of the mapper function.

(And maybe add a comma after “second”?  Not a native speaker.)