LGTM. The only legitimate reason body could be null AFAIK is if the document itself lacks a body tag. Though, given that this appears to be older Firefox specific, we could just be hitting a browser bug here. I wasn't able to find anything in their bugzilla, but this is a safe change regardless.
http://gwt-code-reviews.appspot.com/1111801/show -- http://groups.google.com/group/Google-Web-Toolkit-Contributors
