[8u] Review request: (RT-37168) Mention if a property is configurable via CSS in the javadocs.

[David Grieve]

Steve, Kevin,

I'm looking for your ok on a change to rt/build.gradle that will allow 
me to add @css tags in javadoc. The diff is in the bug. This isn't the 
fix for the bug, but if you don't want to allow the tag option, then I 
need to approach this bug in a different way.

https://javafx-jira.kenai.com/browse/RT-37168