[8u60, 9] review request for RT-37411: [Drag and Drop Linux] setDragView still doesn't work on linux

[Morris Meyer]

David, Kevin et al,

Please review this simple fix for RT-37411.  It is pretty low risk 
vis-a-vis 8u60.

Thanks much.

        --morris meyer

JIRA - https://javafx-jira.kenai.com/browse/RT-37411
WEBREV - http://cr.openjdk.java.net/~morris/RT-37411.01/