8u40 review request: RT-25263 AreaChart has flattened series symbols in the legend

[Jim Graham]

Hi Kevin, Chien,

webrev: http://cr.openjdk.java.net/~flar/RT-25263/webrev.00/
Jira: https://javafx-jira.kenai.com/browse/RT-25263
CC'ing Felipe in case he has any comments from when he worked on this 
code...

                        ...jim