I have setup Webstorm to recognise and compile my coffeescript files.
I have installed the AngularJS plugin and can successfully write my controllers etc in plain o
With webstorm 10 you are going to go to the preferences window and from there select Languages & Frameworks > JavaScript > Libraries. Then click the download button, select TypeScript community stubs from the dropdown at the top of the list, find angular and click download and install.
If you are using jshint be sure to go to the jshint settings find the Predefined option and add angular:true to suppress warnings.