More specifically I have a .gitignore file that was generated when I made my project directory a git repository. That file doesn't show up in the dart editor. I'm assuming it is because of the . prepending the name. I looked around briefly in the menus and couldn't find anything.
The referenced bug is marked as NotPlanned; so it seems support will not be added to Dart Editor.
The good news is that Chrome Dev Editor, which seems to be where Google are putting a lot of their effort for an IDE does show these files fine. Note: CDE is still in preview and doesn't have half of the functionality of Dart Editor (yet).