Getting all the collection names with MongoDB and AS3

At work I've been making on a quick tool to modify objects in MongoDB for our upcoming game. As I remembered reading about some AS3 drivers that allow you to directly connect to a Mongo database rather than need to use a server script, I decided to take a look. And immediately hit a roadblock.
In the main libs I found; @s9tpepper's MongoAS3 lib, and JMCNet's full-mongo-flex-driver; there was no built-in way to get the collections in a database. If you've worked with Mongo before, you'll know that it's slightly important to know that.
Both libs provided access to the Mongo runCommand() command, but no combination of keys seemed to do the job. Of course, you could always just keep a static Array of Strings, but where's the fun in that?
Other languages and drivers usually have a function along the lines of getCollectionNames() and with the help of @dun4n's google-fu, we found out how to do it. Mmmm, smells like a hack!

How it works

So, for a database that looks like this: [...]
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