FYI: rework previous fix

[Roland Westrelin]

I intend to push the following change:

http://cr.openjdk.java.net/~roland/shenandoah/outofloop_wb_correctphi/webrev.00/

It undoes a fix that I pushed some time ago. That fix is the one that
caused us trouble on 8u recently (high memory consumption when not using
shenandoah). Looking at that fix again, I think an alternate fix would
be robuster. I couldn't reproduce the failure that lead to the fix so I
couldn't verify the alternate fix but all testing I've done shown no new
problem.

Roland.