A few days ago, the wysiwyg editor on my 3.5.1 WordPress install stopped functioning, seemingly without provocation. I had not just installed any new updates, themes, or plugins as far as I know. When you click on the "Visual" tab, it simply does nothing. This is occurring in both Chrome and Firefox.
I have tried swtching themes (switched to 2013 with no effect) and deactivating all plugins (except Maintenance Mode, because it is a high traffic domain). I even tried adding my html/js widgets to Unused. Cleared cache after each change. This has had no effect.
Uncaught TypeError: Cannot call method 'add' of undefined -- post.php1172
Uncaught TypeError: Cannot call property 'canvas' of undefined -- load-scripts.php.45
Does anyone know why this might be happening? Please let me know if there is any additional information I can provide.