Visual Editor not functioning

After allowing my site to be automatically upgraded to v3.5, the visual editor isn’t working properly.

When editing an already saved draft, it does not show any of the text. When I select the Text editor, I can see the text. But then I can’t go back to the visual editor.

When creating a new post, it is automatically in the Visual Editor, but doesn’t allow you to actually type anything in. After going to the Text editor, it won’t go back to the visual editor.

I followed the debugging steps (disabling all plugins, changing themes, trying different browsers, clearing the browser’s caches, etc) in
http://ww.wp.xz.cn/support/topic/troubleshooting-wordpress-35-master-list?replies=4

That did not solve it.

I enabled script debugging, which did resolve it. So I turned it back off, and the errors I’m seeing are:
1) Uncaught TypeError: Cannot call method ‘add’ of undefined post.php:1388
2) Uncaught TypeError: Cannot read property ‘canvas’ of undefined load-scripts.php:6
3) Uncaught TypeError: Cannot call method ‘add’ of undefined post-new.php:1299

I can tell that the errors with the add method have to do with tinymce (though I don’t know how to resolve), and I don’t have even a clue about the canvas property.

Can I get some help in resolving these errors?

Thank you.