RFR: 8073100: [javadoc] Provide an ability to suppress document generation for user desired elements.

[Kumar Srinivasan]

Hello,

New webrev at:
http://cr.openjdk.java.net/~ksrini/8073100/webrev.01/

Highlights of the changes:
* treatAsPrivate works as before ie. only under -javafx flag.
    * re-instated the tests removed
    * removed @treatAsPrivate synonym.
* simplified the check for the  existence of DocTree.

Thanks

Kumar

> Hello,
>
>
> Please review [2] as described by [1].
>
> This has been a long standing request from various customers,
> the tag was always available under the -javafx tool option,
> now the new tag @hidden is for general availability.
>
>
> Thanks
> Kumar
>
>
> [1] https://bugs.openjdk.java.net/browse/JDK-8073100
> [2] http://cr.openjdk.java.net/~ksrini/8073100/webrev.00/