[8u40] API Review: [CSS] Reduce CssMetaData boilerplate code

[David Grieve]

The latest API for https://javafx-jira.kenai.com/browse/RT-36510 is 
posted on http://cr.openjdk.java.net/~dgrieve/RT-36510/webrev.03. Please 
see the comments in RT-36510 for details.