RFR : 7129185 : (M) Add Collections.{checked|empty|unmodifiable}Navigable{Map|Set}

[Mike Duigou]

Hello all;

I've incorporated feedback from previous rounds and expect to finalize this 
addition soon.

http://cr.openjdk.java.net/~mduigou/JDK-7129185/2/webrev/

Any review feedback or suggestions of additional tests welcome.

Thanks,

Mike