RFR (S): Heap dump support

[Aleksey Shipilev]

On 12/12/2016 03:48 PM, Zhengyu Gu wrote:
> ShenandoahSafeObjectIterateAdjustPtrsClosure seems a duplicate of
> ShenandoahAdjustPointersClosure in shenandoahMarkCompact.cpp.

Yes, except that mark-compact bypasses the usual fwdptr verification checks with
BrooksPointer::get_raw, which I don't want to do in regular code.

Also, I thought copying it would be more straightforward than making it shared.
We should clean up all these closures at once in some shared file, like
g1OopClosures.* do.

Thanks,
-Aleksey