emberjs/ember.js — pull request #3834 by bcardarella (2013-12-02 02:21:25+00:00)
Title: [FEATURE toggle action]: Actions can toggle a property

A common pattern I find myself doing is a toggle action to call
toggleProperty to switch a boolean value. It would be nice to not have
to recreate this pattern over and over. This PR adds the following param
to the `action` helper:

```handlebars
Show
```