8u40 review request: adding unit test for fromFXImage()

[Jim Graham]

Kevin,

You asked for it, you got it, now you get to review it... ;)

webrev: http://cr.openjdk.java.net/~flar/RT-38846/webrev.00/
Jira: https://javafx-jira.kenai.com/browse/RT-38846

                        ...jim