mozilla/addon-sdk — pull request #584 by ZER0 (2012-09-20 20:51:35+00:00)
Title: Bug 789981 - CSS Style Sheets don't deactivate on addon uninstall

- Unregistering `contentStyle*` calling `destroy` method on every PageMod in PageModManager's destructor.

**Note**: I have to say that I'm not familiar with the `Registry` stuff and how `PageModManager` uses in this context, so maybe there is a better alternative.