RFR (XS): 8196883: G1RemSet::refine_card_concurrently doesn't need to check for cards in collection set

[Kim Barrett]

> On Feb 7, 2018, at 11:25 AM, Thomas Schatzl <thomas.schatzl at oracle.com> wrote:
> 
> Hi all,
> 
>  can I have reviews for this small change that removes obsolete code
> in concurrent refinement processing?
> 
> from the CR: "G1RemSet::refine_card_concurrently tests whether the
> region is in the collection set, skipping refinement if so, with an
> explanation that objects in the cset are about to move. But the cset is
> a collection pause artifact, and is clear when not in a GC pause. The
> test was useful when there was a single refine_card function that was
> used both concurrently and during a GC pause, but JDK-8177707 split the
> two cases into separate functions. It is no longer useful, and should
> be removed."
> 
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8196883
> Webrev:
> http://cr.openjdk.java.net/~tschatzl/8196883/webrev/
> Testing:
> hs-tier 1-5
> 
> Thanks,
>  Thomas

Looks good.