I dug through the code a little bit and found this folder, which contains every single emoji Cloud9 supports. The way Cloud9 seems to have done this is to change, say,
E001, for instance. Then, once the client receives this, it fetches a picture at
/whatever-path/emojis/emoji-E001.png. So, if you’re looking for an emoji, you can either find it in the folder and then search for the file name (minus the extension) in this JSON file, or find the relevant emoji code in the JSON file and look at the image in the folder. I know it’s not a nicely compiled list, and they might have it documented elsewhere, but that was just from a quick look.