RFR (S) 8240948: Shenandoah: cleanup not-forwarded-objects paths after JDK-8240868

[Roman Kennke]

Looks good.

 Let's do the rest carefully. Full-GC requires updating refs by
traversal because we may not be able to parse the heap sequentially.
Traversal should be mostly-ok because it has its own set of closures to
deal with updating refs.

Thanks,
Roman

On 3/12/20 10:43 AM, Aleksey Shipilev wrote:
> RFE:
>   https://bugs.openjdk.java.net/browse/JDK-8240948
> 
> Unfortunately, not much code can be eliminated from conc-mark, because Full GC (and Traversal?)
> share some of that code.
> 
> Webrev:
>   https://cr.openjdk.java.net/~shade/8240948/webrev.01/
> 
> Testing: hotspot_gc_shenandoah
>