Crash on "Show hidden files and directories" [@ nsFileView::SetDirectory(nsIFile*) ]
fix: don't let files be initialized with relative paths.
also fix the directory service to not do that.
r=dougt sr=bzbarsky
git-svn-id: svn://10.0.0.236/trunk@150734 18797224-902f-48f8-a5cc-f745e15eee43