Prevent error about this.domNode not defined when hitting back button from  Tree test page. Refs #2931.
Prevent error about this.domNode not defined when hitting back button from 
Tree test page.
Refs #2931.

git-svn-id: 674a2d6b1e32e53f607eb824547723f32280967e@8743 560b804f-0ae3-0310-86f3-f6aa0a117693

harbalk/delite,harbalk/delite,Sam-Cummins/delite,kitsonk/delite,kitsonk/delite,Sam-Cummins/delite