Fix for NPE when the AWT Viewer is used with an area tree file as input.
Fix for NPE when the AWT Viewer is used with an area tree file as input.

git-svn-id: 102839466c3b40dd9c7e25c0a1a6d26afc40150a@371919 13f79535-47bb-0310-9956-ffa450edef68

apache/fop,chunlinyao/fop,apache/fop,apache/fop,apache/fop,chunlinyao/fop,apache/fop,chunlinyao/fop,chunlinyao/fop,chunlinyao/fop