RFR[XS]: 8238272: Eliminate cast_from_oop to narrowOop*

[Kim Barrett]

> On Jan 31, 2020, at 5:12 PM, Kim Barrett <kim.barrett at oracle.com> wrote:
> 
> […]
> Here's a new webrev:
> 
> https://cr.openjdk.java.net/~kbarrett/8238272/open.01/
> 
> I didn't bother with an incremental webrev, since the new version is just
> a one-line change replacing the previous one-line change.
> 
> Testing: tier1

Ping?  Looking for a second reviewer.