RFR(XS): 8234350: assert(mode == ControlAroundStripMined && (use == sfpt || !use->is_reachable_from_root())) failed: missed a node

[Roland Westrelin]

Hi Martin,

Thanks for reviewing this.

> 1. mode != IgnoreStripMined at the beginning
> 2. (mode == ControlAroundStripMined && use == sfpt) ||!use->is_reachable_from_root()

That's reasonable. I will make the suggested changes.

Roland.