RFR (xxs): JDK-8130823 - VerifyRememberedSets is an expensive nop in product builds

[Thomas Schatzl]

Hi Jesper,

On Wed, 2015-09-02 at 19:53 +0200, Jesper Wilhelmsson wrote:
> Hi,
> 
> Please review this minor fix to change an assert into a guarantee to enable 
> VerifyRememberedSets in product builds.
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8130823
> 
> Webrev: http://cr.openjdk.java.net/~jwilhelm/8130823/webrev.00/
> 

  looks good.

Thomas