8150785: (bf) Hoist slice and duplicate methods up to java.nio.Buffer

[Pavel Rappo]

Hi,

Could you please review my change for JDK-8150785?

    http://cr.openjdk.java.net/~prappo/8150785/webrev.02/
    http://cr.openjdk.java.net/~prappo/8150785/specdiff.02/java/nio/package-summary.html

Thanks,
-Pavel