RFR: 8152821: Merge jdk.internal.misc.JavaSecurityAccess and jdk.internal.misc.JavaSecurityProtectionDomainAccess shared secrets

[Claes Redestad]

Hi,

ProtectionDomain creates both the JavaSecurityAccess and the 
JavaSecurityProtectionDomainAccess SharedSecrets, and since 9 both are 
always created eagerly during early bootstrap. It seems safe to merge 
these two, as suggested, which is a tiny startup improvement and cleanup.

Webrev: http://cr.openjdk.java.net/~redestad/8152821/open.00/

Bug: https://bugs.openjdk.java.net/browse/JDK-8152821

Thanks!

/Claes