RFR (XS) 8182847: Copy class should use assert macros

[Kim Barrett]

> On Feb 16, 2018, at 6:14 PM, coleen.phillimore at oracle.com wrote:
> 
> open webrev at http://cr.openjdk.java.net/~coleenp/8182847.01/webrev
> bug link https://bugs.openjdk.java.net/browse/JDK-8182847
> 
> Tested with tier1-4 on all Oracle platforms in mach5.  Also tested failure case with temporary change (see bug for details).
> 
> Thanks,
> Coleen

Looks good.