Feature summary :
Some websites for example those with a lot of code snippets, rely heavily on the ability to collapse divs

Use case(s)
mw-collapsible class is ignored when using the Mobile frontend, understandably this is for performance reasons, but for some websites would be very helpful to optionally include this capability.

Benefits:
Functionality often being added manually in Mobile.js is already included in the default build we just need a method to expose this.