hg: valhalla/valhalla/hotspot: Fix and cleanup in vwithfield

[Frederic Parain]

Fixing a bug in vwithfield leading to buggy stack management.
Thanks to Mr Simms for having spotted and identify the issue.
I took the opportunity to do a clean up of the vwithfield method,
removing raw pointer arithmetic on the expression stack, using
the frame API instead.

Fred


> On Jun 7, 2017, at 15:39, frederic.parain at oracle.com wrote:
> 
> Changeset: b03e14ea3e9b
> Author:    fparain
> Date:      2017-06-07 15:38 -0400
> URL:       http://hg.openjdk.java.net/valhalla/valhalla/hotspot/rev/b03e14ea3e9b
> 
> Fix and cleanup in vwithfield
> 
> ! src/share/vm/interpreter/interpreterRuntime.cpp
>